THE
ENERGY
OF LIFE
GUY BROWN

Copyright

Fourth Estate

An Imprint of HarperCollinsPublishers 1 London Bridge Street London SE1 9GF

www.harpercollins.co.uk

Published by Flamingo 2000

Published in hardback by HarperCollinsPublishers 1999

Copyright © Guy Brown 1999

Guy Brown asserts the moral right to be identified as the author of this work

A catalogue record for this book is available from the British Library

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Source ISBN: 9780006530473

Ebook Edition © FEBRUARY 2016 ISBN: 9780007485444

Version: 2015-12-31

CONTENTS

Cover

Title Page

Copyright

Introduction

Chapter 1: ORIGINS

Chapter 2: THE STORY OF LIVING ENERGY

Chapter 3: ENERGY ITSELF

Chapter 4: THE MACHINERY OF LIFE

Chapter 5: The Body Electric

Chapter 6: MITOCHONDRIA: THE MONSTERS WITHIN

Chapter 7: THE PACE OF LIFE AND DEATH

Chapter 8: GETTING FAT AND STAYING THIN

Chapter 9: EXERCISE, FATIGUE AND STRESS

Chapter 10: MIND ENERGY

Chapter 11: BRAIN ENERGY

Chapter 12: SEX AND SLEEP

Chapter 13: MOOD, MADNESS AND CREATIVE ENERGY

Chapter 14: HOW TO GET MORE ENERGY

Sources & Further Reading

Glossary

Index

Acknowledgements

About the Author

About the Publisher

Introduction

Every morning of our lives we wake up and reach out from unconsciousness to consciousness, from nothingness to being, from dream to reality. And when the full force of reality hits us, we must choose between falling back into nothingness, or grabbing hold of reality. To wake up and get on with life we need energy: both body energy and mind energy. We need body energy to get out of bed, make the tea, run for the bus, beat our competitors, and drag ourselves home again. Whereas mind energy arouses and motivates us, to actually want to get out of bed and do something. This book is about what energy is, how we get it, and how we lose it again. But in discussing these practical things we will also be touching on more fundamental issues. What is life? How does it work? And why do we bother getting out of bed in the morning at all?

But what is this thing – energy – that divides the strong from the weak, the young from the old, the living from the dead? How does energy animate the body and mind? How does it enable a body to grow, a finger to move, a mind to think? Energy is the basic constituent of the Universe, even more fundamental than matter. Energy is the origin of all change. Every event in the Universe, from the collision of atoms to the explosion of stars, uses energy. And our own bodies, even when in dreamless sleep, require large amounts. To be alive is to be a continuous transformer of energy, a machine transmuting the food we eat and the air we breathe into a dancer’s leap and a poet’s dream.

There is abundant evidence that how energetic we feel is a major element of how happy, healthy, productive and creative we are. It may be more important for our overall well-being to track what boosts or drains our energy, than to follow our calorie intake or bank accounts. Energy is a central aspect of our lives. Without it, our personal world shrinks to a few essential tasks, people, and places: for we have no energy to face anything more than an essential minimum. But with an abundance of body and mind energy our world opens up, as we expand our interactions with people, projects and places to fill all the available time.

Vitality, passion, dynamism, confidence, the ability to concentrate and work without rest, to think fast and coherently, to resist fatigue and exhaustion – in short ‘energy’ – are the essential qualities, above all else, required to succeed in life. Top of the Harvard Business Review’s list of vital qualities for business success is ‘a high level of drive and energy’. Everyone looks for that sparkle in friends and lovers to ‘make things happen’. Most of all, everybody is looking for energy within themselves: the motivation and drive to get up and do something; the endurance, stamina and resolve to carry through what we are already doing and need to do; and the courage and will-power to change direction and break out of the old routines, when necessary. We may know how to do something, but without will and energy, it is not going to happen. Without mental energy there can be no joy, excitement or enthusiasm. But physical and mental fatigue seem to have infected almost everyone: the most common symptom reported by patients to their doctors today is lack of energy. Depression and exhaustion appear to be endemic to our society. Everybody wants more energy.

The Energy of Life follows the evolution of our ideas about biological energy, from their origins in the prehistoric concepts of life itself, to the latest research on the body electric and psychological motivation. The story of living energy twists through various manifestations as the vital heat or pneuma concocted in the furnace of the heart in ancient Greece; as chi energy coursing through meridian lines of the Chinese body; as prana convulsing the body of yogis in India; as the vital force sought by the alchemists in their dreams of gold and life everlasting and through, in more modern times, to the discharge of Freudian sexual energy.

The last fifty years have finally enabled us to answer the fundamental questions of what energy is, and how it drives body and mind. But the answers seem, at first, more fantastical than the questions. Our body and minds are powered by electricity. Our cells are energized by huge electric fields driving vast currents through tiny molecular machines: motors, gates, pumps, switches and chemical factories together creating cellular life. It would be possible to imagine a happy electrical hum within the cell were it not for the incredibly frantic pace of activity, the colossal forces, and sparks flying from the life-threatening leakage of electrons. The electric energy is produced by trillions of bugs that invaded the ancestors of our cells billions of years ago, and thousands of which now live in each cell of our body. But these invaders who appear to live peacefully in symbiosis with the cell, may also be the enemy within. Recent research shows they are the silent assassins and executioners of the cell and are implicated in a multitude of devastating diseases and disabilities, and in the processes of ageing itself, leading to an irreversible decline in body and mind energy.

The energy moving and motivating the mind has always been a mystery. But modern technology now enables us to image and visualize changes in energy inside our brains, from moment to moment, as we think and feel. The brain chemicals and pathways controlling arousal, anxiety and motivation have now been found, so that we are finally close to understanding what excitement and depression are, and how to control them with drugs. We now know that obesity and body weight are regulated by a signal released by fat and acting on the brain, to control appetite and energy expenditure. The origin of sexual libido has been traced back into the dark recesses of the brain. We are beginning to understand how the body and the mind communicate in health and disease, why stress and depression cause illness and why illness in turn causes fatigue.

No matter how fast knowledge accumulates, questions remain: Why do we use so much energy? Why is life so short? Is there a relationship between energy and time? Why does time seem to go faster and life get less exciting as we get older? Why do children have so much energy? Why do the body and mind tire, and why do we need sleep? What is chronic fatigue? What is the mind, and what motivates it? There are no solid answers to these questions yet, but there are fascinating possibilities.

Our feelings of energy and tiredness wax and wane during the day, and during the course of life, in predictable cycles. Perhaps you feel tired now. But what is tiredness and fatigue? Are you exhausted at the end of the day because you have run out of energy, or because your brain is trying to put you to sleep? What is this spectacular daily oscillation in energy level for? Do you get tired as you get older because you are running out of energy, or because your genes are trying to put you to sleep – permanently?

Current theories of body and mind energy are split between many different disciplines and conceptual frameworks. This book seeks to bring these ideas together, to show how central energy is to our lives. Literally everything we do uses energy. It ebbs and flows within us every minute of the day, with every burst of adrenaline and every thought swirling through our mind. During dreamless sleep, the body is still, and the mind empty. When awake the body and mind are in ceaseless motion. Whenever motion appears from non-motion, or activity from inactivity, we say that ‘energy’ is involved. This energy produces the motion or activity. The energy may be stored, or it may be supplied from outside. Thus, when a sleeper wakes, the energy to move and think comes from energy stored in the body and mind. But those stores need to be replenished from external sources. This is the everyday concept of energy: something invisible that produces motion or activity, but in producing activity is used up, so it needs to be replenished. When we complain we are short of energy, we mean that our capacity for physical or mental activity is low, and we need this capacity to be recharged.

There are many words expressing a high-energy state: vitality, vigour, vivacity, strength, arousal, ardour, drive, fervour, stamina, gumption, zeal and zest. Just as many words describe the opposite: lethargy, apathy, timidity, weakness, languor, weariness, tiredness, fatigue, and depression. These words cover many shades of meaning, but what they have in common is the idea of a capacity or desire to do things, beyond the technical skill to perform the particular task. The popular concept of energy has extended into many different capacities and fields; so now we have physical energy, mental energy, sexual energy, emotional energy, psychic energy, creative energy, etc. While the meaning of ‘energy’ in physical science is a much more restricted and concrete one, the flexibility of popular concepts of energy captures something crucial to all of our everyday lives.

The Energy of Life takes the popular and ancient concept of biological energy, and looks at it from the perspective of the latest science. In so doing we will cover a vast territory from history to physics, energetics to psychology, through the evolution of life to the origins of cell death. We will look at how and why energy was discovered. How the delicate machinery of our cells makes the miracles of motion and thought possible. And how that same machinery creates fatigue, obesity, disease, ageing and death. We will also examine how energy is related to the perception of time, why we sleep and dream, the connection between energy and sex, and the link between creativity and madness. Then finally we will return to the more practical question of why we, as individuals, sometimes lack energy, and what we can do to get more.

Chapter 1 ORIGINS

‘In the beginning’ the meaning of energy was inseparable from the meaning of life. ‘What is life?’ was an unavoidable question for people confronted with death and the dying on a daily basis. A newly dead body may appear identical to the live one existing only moments before, but it is missing an important ingredient: life. What is this invisible thing animating the living but disappearing with death?

Important clues are given by the subtle differences between the living and the dead: movement, breath, heartbeat, pulse, warmth, growth, and (less obviously) consciousness. These differences were central to the concept of life (and death) in most early cultures, and are still important to our own modern and scientific ideas of life. But a bare list of the differences cannot give us a general theory of life or death. What is the need for a general theory? Because daily confrontation with death prompted urgent, practical questions: can death be prevented? And if not, can it be reversed? Finally, if all else failed, the ultimate questions: was death the end? What happened to the body and mind after death?

Imagine a caveman bent over his recently deceased cavewoman: with knotted brow, Rodin pose and a thought bubble full of question marks, the dawning thought: ‘What are life and death?’ Of course, no such caveman ever existed – we are merely indulging in a narrative device. But if our prehistoric sleuth can mentally capture the essence of life perhaps he can feed it back into his mate and love once more. However, he must hurry, before her still warm and lovable body rots and turns to dust. To tackle this cosmic conundrum he must decipher the differences between his loved one before and after death. The only clues he has are those he can see, hear or feel; his only evidence the body. He must read the body. The meaning of life is not some grandiose theory, but instead the rather gruesome differences between a live body and a dead one.

The most obvious difference is movement. The dead can’t dance, while the living gaily cavort. In early cultures, such as those of ancient Egypt and Greece, movement was often taken as a sign that the object in motion, even if it was the sun moving across the sky, wanted or intended to move, and thus that it had some kind of mind willing it. But there is some subtlety here: for a dead body can also move. If we lift up the arm and let go, it will fall. If we hold the body up on two feet, and wave its arm, it will stand and wave. If we push up the two ends of its mouth it may even give us a ghoulish smile (assuming rigor mortis has not set in). The essential difference between the living and the dead is not movement itself, but rather spontaneous or willed movement. Willed movement is a sign of mind, a kind of mind energy. It was this concept of self-generated motion that early cultures used to divide the world into the animate and the inanimate. If spontaneous movement was not due to living humans or animals, then it was attributed to souls, spirits, devils or gods. A stone is not living because it does not move of its own accord – even a rolling stone is not living if it has been pushed down a mountain – but an avalanche can suggest the work of an angry god or devil. The apparently spontaneous movement of wind, lightning, sun and planets was associated with spirits or gods, by the ancient Egyptians, Chinese, Greeks and American Indians. Indeed the distinction between living and non-living things was not as clear or important then as it is now, because the world was full of supernatural spirits, and even inanimate objects could be seen to have intentions and desires.

We should note that the type of movement regarded as ‘self-generated’ is dependent on the theory being used. Thales, known as the ‘grandfather’ of Greek philosophy and science who was active around 600 BC, thought that a magnet had a soul because it moved iron. It may be because all things move in apparently spontaneous ways in certain circumstances (e.g. when dropped) that he famously said, ‘all things are full of gods’. Around 350 BC, Aristotle, perhaps the greatest ever philosopher and scientist, described God as the ‘unmoved mover’, the first source of free, unforced movement and change. Today we have gone to the other extreme, and many scientists believe that there are no spontaneous movements or change, even within humans (because each change is caused by a prior change via some mechanism), and thus there is no need for gods, souls, or spirits. However, the modern concept of energy has replaced gods and spirits as the source of all movement and change in the Universe.

When our caveman-penseur presents his beautiful new hypothesis (that the difference between life and death is self-generated movement) at neighbouring caves, it is not long before some overly smart cavewoman points out the flaw in his argument, that when he is asleep or knocked unconscious, he has no self-generated movements yet is, to all appearances, alive. She may continue that anyone with any sense knows that in such circumstances the way to tell the living from the dead is from subtle, internal movements: breathing, the pulse, and the heartbeat. These internal motions are still used today in the diagnosis of life or death, and it was the investigation of them, and their associated processes, that led to our modern concepts of life and body energy.

Breath was central to ideas of life and energy in most early historical cultures. In Egypt, breath was associated with ka, a soul which separated from the body after death. Breath-energy was known as chi in ancient China, thymos and later pneuma in Greece, and prana in India, although each of these terms meant different things to the different cultures involved. The first entry and final exit of breath from the body were synonymous with life and death. In Greek legend, the first man was fashioned by Prometheus from earth and water, but the soul and life were breathed into him by the goddess Athena. If breathing is stopped, it leads to loss of consciousness and finally death, and so it would have always been obvious that life depended directly on breathing. But breathing is associated with much more than just staying alive. Changes in breath and breathing occur during most emotional states, as is recognized in phrases such as: ‘she took his breath away’; ‘panting with eagerness’; ‘gasping with astonishment’; ‘sobbing with grief’; and ‘yawning with weariness’. These emotions are associated with sounds and chest movements, which might lead us to believe that all emotions are located in the chest and expressed in sound (as in the phrase ‘get it off your chest’). We may also consider talking itself to be a kind of breath, as words appear to be carried by the breath from the chest. In pre-literate and semi-literate cultures, thought was often considered to be a kind of talking, perhaps because much thinking was done out loud. And as talking and expressions of emotion were connected with breathing, then thought and emotions could be associated with the breath in the chest.

In the pre-Classical Greece depicted in the Iliad and Odyssey, thought and emotion were seen as a kind of breath-energy known as thymos, which was stored in the lungs or chest (phrenes), and breathed forth as speech, anger or grief. The Greeks appear to have conceived thymos to have been a hot vapour, coming from the body or blood, an idea perhaps inspired by the vapour in breath visible on a cold day, or by the vapour escaping from gushing blood. Thus, we have images of the spirit and soul as a partially visible vapour, as in the soul escaping from the body in a dying man’s final breath. The root of the modern word ‘inspiration’ means both breathing in and the receipt of divine or supernatural thought and feeling. This usage may derive from Homer, where often exceptional thought, feeling, courage, strength, anger and dreams were derived from the gods, who ‘breathed’ them into humans, as thymos to be stored in the chest/lungs, before the humans exhaled them out as speech, feeling, willed action, or thought.

Breath may well have been important to conceptualizing life in another way. It is (usually) invisible, yet when we blow hard our breath can move things and we can feel it against our hands. In this respect it is like the wind, which was often conceived of as the breath and will of gods. Thus, breath was an invisible source of movement outside the body, and might therefore act as an invisible source of movement within the body, to move the limbs and vital functions.

In China breath-energy was known as chi (pronounced chee, as in cheese, and sometimes written as qi) and chi was a fundamental component of the Universe. According to the Huangdi Neijing: ‘That which was from the beginning in heaven is chi; on earth it becomes visible as form; chi and form interact giving birth to the myriad things’. There are many different types of chi, sometimes earthly and material, at other times heavenly and immaterial, and its effect can be seen in the growth of a plant, the power of thought, or the energy that activates any process. Life originates from an accumulation of chi; and death from its dissipation. Chi also means ‘air’, but air was thought to be a non-material empty space; thus chi is not a material substance, but rather a process, force, or energy. Within the body chi is known as true chi, and was derived both from air by breathing, and from food and water by ingestion. The Huangdi Neijing states: ‘True chi is a combination of what is received from the heavens and the chi of water and food. It permeates the whole body’.

True chi circulates around the body via twelve main pathways or meridians. These meridians are mapped onto the surface of the body, so that acupuncture can control the energy flows, although the meridians cannot be identified with any anatomical structures in the body. However, each meridian is also associated with a particular organ and function, and the flow of chi along the meridian actualized that function via the transforming action of chi. As the Chinese put it:

‘The meridians are the paths of the transforming action of chi in the solid and hollow organs’ (Yijiang jingyi).

There were several different types of chi associated with different organs and their functions:

‘Thus one is able to smell only if Lung chi penetrates to the nose; one can distinguish the five colours only if Liver chi penetrates to the eyes; one can taste only if Heart chi penetrates to the tongue; one can know whether one likes or dislikes food only if Spleen chi penetrates to the mouth’ (Zhongyixue gailun).

The Chinese thought of chi as flowing along the meridians, much as water flows along a riverbed. The meridians and their smaller branches irrigated the whole body, as a river and its canals irrigate the fields of a valley. If a disease arose in the body it affected these rivers of life, so that either no water flowed at all (lack of chi), or the river was blocked at a particular point, with excessive water and flooding above the block (swelling, and congestion of chi) and insufficient water below the block (atrophy, lack of chi). It was thought that the acupuncture needle removed the block, either directly or by increasing the force of the stream. In order to live a long and vital life people were encouraged to nurture their chi. And this was achieved by moderation in all things, avoiding either excess or lack in their diet, exercise, or sex. But also by avoiding external sources of ‘bad’ chi, such as cold, damp, fright, or even, sex with ghosts.

Indian concepts of breath-energy – prana – may have predated and inspired those of Europe and China. Hindus teach that in addition to the physical body, there is an astral body, occupying the same space and connected to the physical body by a thread, severed at death. The vital energy, prana, flows through this astral body within thousands of channels – nadis – connecting seven energy centres or wheels of light, known as the chakras. Health and consciousness can be controlled by regulating the flow of prana, using pranayama (breathing exercises), asanas (yoga postures), and meditation. Normally, most of our prana is carried by the Ida and Pingala nadis, which pass through the left and right nostrils respectively, and carry cooling moon energy or warming sun energy respectively. Yogis claim to control their level of consciousness by minutely regulating their breath and thus the flow of prana, by changing the depth, rhythm, and nostrils used for breathing. In one type of yoga, ‘Kundalini Yoga’, the yogi uses breathing techniques and meditation to mobilize the creative female energy (Kundalini) latent in all – men and women. This energy is symbolized by a sleeping snake coiled around the bottom chakra at the base of the spine. The yogi attempts to create an inner heat that rouses the serpent-power from its sleep, driving it up the central nadi along the spine, piercing each chakra in its path, and absorbing their energy, until finally uniting with the male energy of the crown chakra at the top of the head. Kundalini may be experienced as if a bolt of electric charge were passing up the spine, and, if successful, results in a higher level of consciousness where all illusions are dispelled.

The heart and heartbeat were associated with the soul or spirit in most early cultures, and it is not hard to see why. The heart beats rhythmically and continuously at the body’s centre from birth to death. It speeds up during strong emotions and exertion. It slows down with age and rest. Its stopping is synonymous with death. It is the only internal organ with spontaneous motion, and can be extracted from the body still beating. It is associated with the pulse and the movement of the blood. In Egypt, the heart held the power of life and the source of good and evil. According to the Book of the Dead, the heart of each human was weighed on a scale against a feather after death to determine the balance of good and evil, and thus the fate of the spirit. In many Indian and Chinese languages, the words for heart and mind are more or less synonymous. The Toltecs and Aztecs of ancient Mexico ripped the still-beating heart out of their human sacrifices to offer to their sun god. Most early cultures located consciousness and emotions in the heart (or chest/lungs). Interestingly, the soul (psyche), which survived death and produced new life, was often located elsewhere, usually the brain. However, many early cultures did not have such a strongly dualistic concept of the separation of mind and body. Thus it is not always appropriate to talk separately of the mind and body, or of locating the mind in a particular organ of the body.

The Ilongot, a society of headhunters with relatively little contact with the modern world, living in the Philippines, have a word liget which means something like energy and anger. This force arises in the heart, because for them ‘motions of the heart are emotions’ – a belief not far removed from modern, psychological theories of emotion. However, the word liget is also used by the Ilongot in ways that we might regard as metaphorical. For example, chili gives liget to a stew, ginger revitalizes liget in a killer, and winds have more liget when obstructed. Liget is also revealed in people when they pant and sweat, flowing inwardly and generating redness in the self. It is dynamic, organic, chaotic violence, and also the stuff of life.

Early cultures often did not distinguish between the literal (or concrete) and metaphorical (or abstract) use of a concept – the concept of metaphor was only invented by Aristotle in the fourth century BC. So the ancient Greeks used a word such as psyche to refer to both a substance in the body and the behaviour of the soul. The temptation is to say that the ancient Greeks and other early cultures were more literal minded and their thought was less abstract. Yet, most modern discourse also fails to distinguish between literal and metaphorical uses of words. The word ‘energy’ is popularly used to describe everything from the charge supplied by electricity wires, to the intensity of an artistic performance. One manifestation of literal mindedness is the tendency to explain a property of something as due to a discrete substance within the thing (an unfortunate tendency known as ‘reification’). For example, Dr Pangloss, in Molière’s Candide, explained falling asleep as due to a ‘dormative principle’ within the body or mind. Similarly ‘living’, which is essentially a state or way of being, has been explained in terms of substance: life or vis viva (the life-force). Doing things intensely or passionately has been explained in terms of the possession of ‘energy’, the energizing substance swirling around the body or mind. In some cases, thinking of a property or behaviour as a ‘thing’ can be helpful, but more usually scientific or intellectual progress has been made by explaining ‘things’ in terms of processes. Thus most scientists no longer think of life or energy as things to be explained by separate substances, rather they are particular arrangements or processes of matter. However, in popular culture, life and energy still have mixed literal and metaphorical meanings, which partly reflect those of much earlier times.

In early cultures the heart’s beating was associated with the movement of blood in the body, which was indicated by the pulse and by the rhythmic spurting of blood from severed arteries. The pulse was used in the diagnosis of health and illness, vigour and death in the medicine of ancient Greece, India and China. The violent colour of blood, its dramatic eruption from wounds, its ability to rapidly congeal once outside the body, and the fact that its loss was associated with death, all contributed to the idea that it was intimately connected with life. Indeed for some cultures, blood was seen as the substance of life itself. Many stone-age burials have been discovered where the bones have been covered with a red ochre probably representing blood, which would suggest that the connection between blood and life (or death) was very early indeed. The drinking of blood, either literally or symbolically (as in the Christian Eucharist), was a means of transferring the soul/energy of the human, animal or god to the drinker.

Our caveman has now got some theories, but it does not seem to be doing his cavewoman any good. She has gone cold. The caveman now needs to add one more item to his list of differences between living and dead: body heat. The body temperature of living mammals and birds is normally higher than their surroundings, cooling to that of their environment at death. If our body temperature is lowered by more than a few degrees, if for example we fall into freezing water, then we rapidly die. Clearly heat has an important connection to life. In pre-industrial times, the only significant producers of heat were animals, fire and the sun. Aristotle, for example, thought of the life-force partly as a kind of fire inside the body. And the association between heat (and movement) and the life-force, may well explain the widespread belief that the sun was a god, and the use of fire in religious rituals. In fact there are a number of other important similarities between life and fire: both are produced by the burning of organic matter (fuel/food) with air (supplied by a bellows or breathing), which generates heat, movement, and residual waste (ash/faeces). This analogy was important both in ancient Greece and in much more modern times. For it was the key concept in the development of the modern scientific idea of body energy, although the theory could not be used productively until chemical concepts of burning were developed by Lavoisier in the eighteenth century.

Back with our caveman, things are looking bleak. The cavewoman’s body has started to decay. First the flesh rots away, leaving the skeleton, then the bones themselves disintegrate to dust. Although the process is slow, its effect is dramatic: we start with a highly organized human body and end with a pile of dust, which merges into the soil. There is obviously little hope of reversing this process, and nowhere for the soul to hide afterwards. This is clearly the great disaster of the human condition. Many cultures have expended immense efforts trying to either prevent or circumvent this problem. The ancient Egyptians were the most zealous, utilizing mummification, pyramids, tombs, sacred objects, temples, an extensive priesthood, literature and mythology to evoke a whole parallel world beyond death. In Egypt, bodies were at first buried in dry sand in which they could survive for up to a thousand years, but were shrivelled and dried out. Subsequent use of stone coffins resulted in the flesh disappearing – supposedly eaten by the stone. This is the origin of the Greek word sarcophagus (meaning ‘flesh eating’) perhaps reflecting a prehistoric notion that the body and soul of the dead could enter into and be preserved in stone. The bodies were, in fact, eaten by micro-organisms too small to be seen. The Egyptians developed mummification to prevent this process, although of course lacking any knowledge of the existence of bacteria. Mummification was, however, never entirely successful, and the final resort of both the Egyptians and later cultures was to circumvent the problem by favouring the idea that the mind or soul could separate from the body at death, and either live independently (in heaven or another world), or in other objects (such as in statues), or another body (reincarnation).

The decay of the flesh leaves the bones. Some cultures believed that the bones represented the essential core of the human, the flesh its disposable clothing. The bones contained a vital fluid, which we would now identify as the marrow encased by major bones, the spinal cord encased by the spine, the brain encased by the skull, and the cerebro-spinal fluid permeating the cavities of the brain and spine. All these ‘bones’ surround, as if protecting, a greyish-white gelatinous material or fluid, which in ancient Greece was thought to be the origin of semen, another off-white gelatinous fluid. Thus, semen was thought to be derived from this vital gel, a kind of creative force, constituting the brain, spinal cord and bone marrow. The Romans consequently believed that men’s tiredness after orgasm and ejaculation was due to the draining of creative force throughout the body. The myth that masturbation causes blindness may originate from this ancient concept that the sperm partly derives from the brain. In Greek legend, gods and goddesses were born directly from Zeus’s head (Athena) or thighbone (Dionysus), because this is where the creative force was thought to be located. The belief that bones were the essential core of the human being, encasing an individual’s procreative powers, may have motivated the preservation of the bones of ancestors in many cultures.

The body’s decay after death appears the counterpart of its growth in life. The growth of the body is dependent on food, and it is all too evident that when a human stops eating, they stop growing, shrink, then die. Clearly there was something in food or in eating that was related to life, and this link was all the stronger because food consisted of recently dead animals or plants. Food could thus be thought of as containing either a soul or soul-nourishment. In most early cultures, there were religious rites involving human or animal sacrifice and the eating of the flesh. Often the food was blessed or otherwise transformed so that a god or soul might enter and be absorbed into the body of the eater. The Christian mass is partly derived from earlier Greek Orphic and Bacchic rituals, where food was magically transmuted into the body and soul of a god, which then entered into the body and soul of the person eating. A version of this is described in Euripides’s Bacchae, where the normally well-behaved, upper-class ladies of Athens achieve an ecstatic state, hunting a wild animal representing the god Dionysus, tearing it limb from limb and devouring the raw flesh. This was a means of obtaining ‘enthusiasm’, which in Greek means the entry of a god into the person. Thus, enthusiasm is a kind of mind energy, and these rituals were a means of obtaining it.

The idea that food was incorporated into the body – that when eaten, the substance of the food became the substance of the body – predates Classical Greece, but just how this transformation might occur was not elaborated until the Greeks devised various schemes. One idea was that food was broken down and transformed into blood, then congealing (as in blood clotting) in various ways to produce the body’s organs. While this might explain the growth of children, it did not really explain the fact that although adults do not grow, they require large amounts of food. Later the idea of ‘dynamic permanence’ was developed by Alcmaeon in the sixth century BC, according to which the structure of the body was continuously breaking down and being replaced by new structures and substances derived from food. This would account for the fact that the body slowly decayed after death, when no food could be eaten. The general concept that material things consist of smaller components, which can be rearranged to give all the different forms or structures of things (such as food or the body), was an extremely important and fruitful one. It was particularly developed by Greek philosophers, such as Plato and Democritus, leading to much speculation as to what the simple components might be, for example water, fire, air or earth or atoms of different shapes.

During illness and starvation, the fat of the body shrinks, while in times of health and plenty, it expands. Until comparatively recently, fat was often associated with health and riches. Some Andean Indians still associate the fat with the spirit, and thus when a man ‘fades away’ in chronic illness or starvation, his spirit fades away too, often thought to have been stolen by a sorcerer. Fat, blood and air are the basic body fluids in traditional Andean physiology, and fat is the energy principle distributed from the heart via a system of channels and rivers mirroring the hydraulics of the Andes. This imaginative physiology is indeed partly based on an analogy of the body with the mountains and rivers, so that the head is like the mountain peaks lost in the clouds, while the legs are the river valleys. Illnesses associated with particular parts of the body can be treated by offerings of coca, blood and fat at earth shrines located at appropriate parts of the mountains. In the modern West, where food is plentiful and wasting illness rare, being fat now has the connotation of being unhealthy and poor. But, of course, only a couple of hundred years ago a rotund outline was celebrated, and the skinny figure, favoured today, was feared and pitied.

Our caveman is now distraught. He has watched his mate die: first she stopped moving, then she stopped breathing, her heart and pulse stopped, then the heat left her body, which then started to decay leaving bones and then dust. Watching this process, he has formulated new ideas about life, but these are completely useless in actually dealing with death. Many thousands of years later, we are in the same position: although we know much more about death, we are completely incapable of reversing it. However, let us return to our caveman, who is now in a reflective mood. Many of the differences between the living and the dead are visible and obvious, but perhaps the most important difference is neither visible nor obvious: what happens to the mind? What happens to our perception, thoughts, feelings and will at death? Thoughts, feelings and perceptions are not visible in other people, even if we open up their bodies, and there is no obvious machinery for producing them inside the body. The caveman could not see his mate’s thoughts and feelings when she was alive, so it is conceivable that when dead she is still capable of producing them, although they remain invisible to him. Perhaps the mind or soul enters the body at birth and leaves it at death. Accordingly, the mind of the caveman’s mate may still be alive though her body is dead and gone. This thought may not provide the caveman with much immediate relief, but implies that when he himself dies his mind may survive in some form, and may even enable him to meet up with his mate again.

Different cultures had quite different ideas about whether and in what way the mind might separate from the body at death. But the ancient Egyptians, Indians and Greeks, believed that the mind could survive death. This belief has obvious repercussions on how we view the relations between mind, body and matter generally. If the mind can separate from the body at death and survive as an invisible but active entity, then we could conclude that life consists of two separate entities: an invisible active mind (or soul) which occupies a passive material body. Furthermore, all other entities in the world might also consist of a similar combination of mind and matter. This dualistic distinction between active mind (or spirit) and passive matter foreshadows that between energy and matter, which replaced it: the modern concept of energy has its ancestors among the spirits.

Early explanations of the world attributed intentions or desires to objects, and interpreted events in terms of the desires of spirits and gods. This type of explanation (known as ‘teleological’ or ‘intentional’) mirrors that which we use to explain other people’s behaviour. Thus, if someone hits me over the head with a baseball bat, I might explain this behaviour by attributing it to the attacker’s anger or his intention to rob me. Similarly, if a stone fell on our caveman’s head he may have seen this as the anger or intentions of a spirit, god or even the stone itself. Nowadays, we would look for a ‘mechanistic’ explanation of such an event (for example the stone fell from a building), rather than ascribing evil intentions to the stone or the event itself. In the ancient world, there could be relatively few genuine ‘accidents’ because most events were thought intended by someone, something or some god. Thus almost everything was seen as meaningful; in complete contrast, today most physical events (such as atoms colliding or the Universe exploding) are thought intrinsically meaningless and accidental, except where human intentions are involved. And even where humans are involved, scientists often prefer mechanistic explanations. For example, the scientist may trace that blow to the head with a baseball bat to the effects of the attacker’s upbringing on his brain biochemistry, rather than a premeditated intention to rob me.

Modern science is based on mechanistic rather than teleological explanations, making a strong distinction between passive matter and the invisible mind. And the advance of science has caused a gradual retreat of intention (and mind) from the world: first from non-living matter, then from the body to the brain, and, more recently, attempts have been made by both philosophers and neuroscientists to banish it from the brain itself. Yet as individuals we prefer intentional or anthropomorphic explanations of the world, rather than cold mechanistical explanations. We prefer to think that people and animals do things because they want to, rather than because their brains make them do these things. We like to see the world and Universe as having meaning, rather than being meaningless accidents. Part of the reason science alienates people is its rejection of intentional explanation; and perhaps in turn much of the appeal of religion and literature could be their generous use of anthropomorphism and intentional explanation. You may notice as you read this book that the parts that describe the behaviour of molecules and cells in terms of their intentions, wants or needs, are more readable than the strictly scientific parts cast in terms of cold mechanism. And, moreover, there may well be a good mechanistic explanation of why we prefer intentional explanation, which is that it is hard-wired into our brains. Recent psychological research indicates we develop the ability to attribute intentions to others at the age of three, and children who fail to develop this ability (perhaps because of brain defects) are much more likely to become autistic and unable to interact functionally. Thus, our preference for intentional explanations of other people and the world is because that’s how our brains work, presumably because such explanation has been successful in promoting survival during evolution. However, during science’s evolution, it has been found that intentional explanation is relatively unsuccessful in predicting the behaviour of the world in comparison to mechanistic explanation.

The relevance of intentionality to energy is that the concept of energy has evolved partly to replace intentional explanation. Energy has replaced gods, spirits and inanimate forces as the source of all motion and change in the Universe. But fundamental theories and concepts (such as mind or energy) are not labels that can be attached to the world without distorting it, but are rather like a pair of coloured spectacles through which we can see and interpret the world. If we are short-sighted, it may be impossible to see the world at all without some spectacles (or some theory). Or the spectacles may be locked on (as happened to Dorothy and her companions in The Wizard of Oz), or imprinted in our brains, so it is well-nigh impossible to see without them. The concept of energy is one basic idea through which we now perceive the world. And we have already seen how the origin of the concept of energy is rooted in even more basic ideas about life, movement and mind. In the following chapter we follow these ideas’ evolution into our current conception of energy.

Chapter 2 THE STORY OF LIVING ENERGY

The modern concept of energy originated in the nineteenth century, a child of the industrial revolution, but its origins extend back to ancient Greece, amongst the elements, humours and spirits of the classical world. We will follow the evolution of these ideas of energy and life up to the present, as it is extremely difficult to understand the current concept of ‘living energy’ without seeing where these ideas came from.

THE ELEMENTS, HUMOURS AND SPIRITS OF THE CLASSICAL WORLD

Science started in ancient and Classical Greece, and it is there that we can begin to pick up the trail leading to our current ideas of energy and life. The Greeks were astonishingly creative thinkers. Indeed it is almost impossible to characterize clearly what the Greeks thought about anything, because they thought so many different things about any one thing, most of them mutually contradictory. (Much like the White Queen in Through the Looking-Glass, who could believe six impossible things before breakfast, without spoiling her appetite.) Indeed the Greeks were spectacularly wrong about many things. And this in itself is important because for almost two thousand years after the fall of Athens, Greece’s intellectual heirs in the Hellenic, Roman and Islamic worlds, and in Medieval and Renaissance Europe believed that whatever the Greeks thought was the unquestionable truth. The thoughts of the wise men of Greece on philosophy, science and medicine were held in the same awe and reverence as those of Moses, Jesus and Mohammed on religion and ethics. Now we know that many of the ‘truths’ discovered by the Greeks are ‘false’, but the forms of their ideas, the type of questions they asked, and the ways they went about answering them, have had a fundamental influence on the development of modern knowledge and ideas. Were it not for this relatively small number of thinkers in ancient and classical Greece, science, philosophy and western culture as we know them would not now exist.

Empedocles (c. 490–c. 435 BC) was one of the greatest all-rounders of all time, exemplifying the enormous diversity and creativity of ancient Greek thinkers. Born to an aristocratic family in the city-state of Acragas, Sicily, he assisted in a coup against the oligarchy ruling the city and was offered the crown. He refused, establishing instead a democracy, and becoming himself a politician. But, in his spare time, he also managed to be one of the greatest poets, scientists, philosophers, and doctors of his age. As if this were not enough, after banishment and exile from his home state, he became a prophet and god. Legend has it that he could work miracles, control the winds, restore the dead to life, and killed himself by jumping into the volcanic crater of Etna to prove his divinity. Whether this leap did in fact prove this or not, history does not say, though apparently all that remained of Empedocles physically were his sandals. However, his thoughts remained to haunt the intellectual landscape for over two thousand years.

Empedocles devised the theory of the four elements, described as the most successful scientific theory ever, in terms of popularity and longevity, although it was not, of course, correct. It held that everything in the world consisted of a combination of only four elements. This theory appears to be a diplomatic compromise between earlier contradictory ideas that the world consisted solely of water (Thales), an unknown and unknowable substance (Anaximander), air (Anaximenes), or fire (Heraclitus). Empedocles suggested that there was not a single fundamental substance at all, but rather four elements (or ‘roots’ as he called them): earth, fire, air and water. The advantage of having four elements rather than one, was that it was obvious to anyone that the world consisted of an incredible diversity of things, and it was hard to explain this diversity if everything consisted of the same single substance. It was also difficult to explain how anything could change, if everything was, in essence, the same. Empedocles suggested that each different type of thing in the world consisted of different proportions of the four elements, and further that change was due to exchange of some of its constituent elements. For example, he said that bone was composed of fire, water and earth in the proportions 2:1:1 and flesh was composed of all the elements in equal proportions.

However, change could not just be left to the elements. After all, why should objects alter if there was only inert substance in the world? Why should rocks fall? Why should volcanoes explode? Why should thunder and lightning wrench the skies? Change was a big problem for the Greeks. It is also intimately related to energy, as energy can be thought of as the hidden source and cause of change. How were the Greeks to explain it without invoking gods or souls or minds? How could matter alone cause change? How could something new appear from nothing? Empedocles proposed that, in addition to the four elements, there were also two forces, which he called ‘love’ and ‘hate’. Hate (or ‘strife’) pushed things apart, while love pulled them together again; and when the two forces were balanced there was no change, a standoff. This sounds like a plot for a romantic novel, but Empedocles partly conceived of love and hate similarly to the modern conception of a force, as an inanimate pushing or pulling between matter. Thus, Empedocles’ overall conception of the world as consisting of different immutable elements, pushed and pulled by forces, so that change is due to chance and necessity rather than purpose, is strikingly similar to that of nineteenth-century physics. This similarity is no accident, of course, since the modern concept is partly derived from Empedocles.

Empedocles’ view of the world does, however, diverge radically from the modern in many ways: he also saw the two forces, love and hate, in a religious sense, as a struggle between good and evil (with the four elements each identified with a different god). His scheme of things also differs from ours in that his elements correspond more to the modern phases of matter (solid, liquid, gas, and plasma) rather than to modern elements (such as hydrogen, oxygen, nitrogen, and carbon). This difference partly arises from the fact that Empedocles appears to have rejected the idea of empty space – the void or vacuum – a space where there was nothing, no elements or anything else. Since he had shown that air was a substance, he saw no reason to believe in empty space between the elements. Thus he conceived of the elements as homogenous substances, which blended together when mixed, like different-coloured paints.

Earlier thinkers (such as Anaximenes) and later thinkers (such as Democritus) took the more modern view that a substance consists of a vast number of small particles separated by empty space, and conversion from liquid to gas is not due to a change of elements, but rather to the elements moving much further apart. Thus, ice consists of water molecules held rigidly together, while liquid water consists of the same water molecules flowing over each other, and steam, or completely evaporated water, consists of the same water molecules very far apart. The Atomists – Leucippus and Democritus (c. 460–370 BC) – pushed this view of the world to its most materialistic extreme, by taking Empedocles’ world, ridding it of its religious components, but adding the void. Thus, their view was that there was nothing in the world except a vast number of tiny particles (atoms) moving through empty space. Each of the four elements had a different shaped particle, and this shape determined the properties of the element. This explanation of the world had great advantages over the no-void view, because it could explain easily how the elements could mix and then separate: particles simply passed between each other; whereas this was hard to explain if there was no empty space between elements. Similarly, Empedocles had considerable difficulty explaining why the millions of things in the world had such startlingly different properties, if only differing in the proportions of the four elements. Why should a difference in proportions cause new properties? Democritus (and modern science) could explain this by the arrangement of the atoms within the object. New properties arose from new spatial arrangements or configurations of the atoms. There were an infinite number of ways of arranging atoms of four elements, and consequently an infinite number of possible things or materials. This is the essential secret of the success of modern chemistry and biology: explaining the properties of things in terms of the microstructure of the elements of which they consist. Unfortunately for the Atomists, the technological means did not exist in Greece to probe the microstructure of things, and thus test their theories.

We have been pursuing these ideas about matter, because they lie at the root of modern notions of energy. But Empedocles was far more than a creative physicist (physis was Greek for nature), he was also an inventive biologist (bios, Greek for life). According to Empedocles, the body’s flesh and blood consisted of equal proportions of all four elements, and these attracted similar elements from the environment. Thus, the same four elements constituted non-living and living matter, mind and the immortal gods. The blood circulated from the heart to the surface of the body, where air was taken in through the pores, and back again, alternately expelling and drawing in air. The motion of blood in and around the heart created thought, and so the heart was seen as the organ of consciousness. But Empedocles had a very concrete view of consciousness, seeing for example, thought as simply blood in motion. Perception occurred by elements in the blood meeting and mingling with the same elements in the environment. An external object was perceived by some elements from it entering the body and meeting the corresponding elements in the body, and their meeting or mingling was perception. Nutrition occurred through direct assimilation, that is, the elements of the body attracted similar elements in the environment to them, and these new elements fitted in place to form the growing body.

The theory of the four elements was astonishingly popular and long-lived, lasting from the fifth century BC until the chemical revolution of the seventeenth century. Yet it is hard to see quite why thinkers stopped at only four elements. Aristotle suggested a fifth – the ether – to compose all extraterrestrial things. The Chinese used five elements also (or phases): water, earth, fire, metal and wood. In modern science we have about 100 different chemical ‘elements’, which can combine to give an infinite number of possible molecules. But at the beginning of the twentieth century the Cambridge physicists J. J. Thomson, Ernest Rutherford, and James Chadwick discovered that these chemical elements were not in fact elements in the classical sense (fundamental and indestructible particles of matter), because they were destructible and composed of three simpler, indestructible particles – the proton, electron, and neutron. And these three particles were later found to interact via a fourth (short-lived) particle – the photon. Therefore, Empedocles’ four elements and two forces theory is, in outline, not that dissimilar to much more modern theories of the Universe.

Hippocrates (c. 460–377 BC) is called the founding father of medicine, and his theories of disease, cure and physiology influenced medicine and biology up until the eighteenth century. However, his own life is so mythologized that it is impossible to distinguish the basic events of his life, or even whether he really ever existed. According to legend, Hippocrates was a physician from Cos, and he practised medicine in Thrace, Thessaly and Macedonia, before returning to Cos to found a school of medicine. This school flourished from the late fifth century to the early fourth century BC, producing a vast number of highly original medical texts. Copies of around seventy of these books survive. These were conventionally attributed to Hippocrates, although he probably wrote none of them himself. The defining characteristic of Hippocratic medicine was its rejection of religious and philosophical explanations of disease, and its search for an empirical and rational basis for treatment.

Since prehistoric times, disease had been thought caused largely by gods, evil spirits, or black magic. A cure could thus be effected by ejecting the sin, spirit, or magic from the sufferer via various processes of purification. In Greece, traditional medicine was practised by priest-physicians in temples dedicated to the god Asclepius. In these temples of health, disease was apparently diagnosed partly on the basis of dreams and divination, and partly on the symptoms. Cures were half rituals and spells, and half based on fasting, food, drugs and exercise. According to later legend, Hippocrates was descended from the god Asclepius and brought up on Cos as son of a renowned priest-physician. The relationship between secular medicine (represented by Hippocrates) and religious medicine (based on faith healing or magic) in ancient Greece is difficult to discern, although apparently not as antagonistic as today.

Hippocrates and his followers accepted the doctrine of the four elements as an explanation for the natural world, but their concern as doctors was with disease’s causes and treatment. The four elements – earth, fire, air, and water – cannot be seen in anything approaching a pure form in or on the body. Also they knew relatively little about the inside of the body, because dissection was prohibited on both religious and ethical grounds. So the Hippocratics concerned themselves with what they could see and use in the diagnosis of disease, particularly the bodily fluids: blood, saliva, phlegm, sweat, pus, vomit, sperm, faeces and urine. Gradually the doctrine evolved that there were only four basic fluids (humours): blood, phlegm, yellow bile, and black bile. Blood can appear in cuts, menstrual flow, vomit, urine or stools. Phlegm is the viscous fluid in the mouth (saliva) and respiratory passages and comes out through the mouth and nose in coughs and colds. Yellow bile is the ordinary bile secreted by the liver into the gut to aid digestion; it is a yellow-brown fluid that colours faeces. The identity of black bile is not entirely clear, perhaps originally referring to dark blood clots, resulting from internal bleeding, which may appear in vomit, urine or faeces. However, the four humours did not only refer to these particular fluids, but were thought to be the body’s basic constituents. Health was thought to be due to the balance of these humours, and ill health an imbalance of the humours. Epilepsy was, for example, thought to be caused by an excess of phlegm in the brain blocking the flow of pneuma (vital spirits) to the brain. Thus treatment sought to restore the balance between the humours by removing the humour that was present in excess, for example by bloodletting, purging, laxatives, sweating, vomiting, diet or exercise.

The four humours (blood, phlegm, yellow bile, and black bile) were associated with the four elements (air, water, fire and earth), the four primary qualities (hot, cold, dry and wet), the four winds, and the four seasons. A predominance of one humour or the other gave rise to four psychological types. Thus, the ‘sanguine’ type, resulting from a dominance of blood, was cheerful and confident. ‘Phlegmatic’ types (with too much phlegm) were calm and unemotional. ‘Choleric’ or ‘bilious’ people (with too much yellow bile) were excitable and easily angered. ‘Melancholic’ types (too much black bile) were, obviously, melancholy, that is sad or depressed, with low levels of energy. This was the earliest psychological classification of character or temperament, and was used to categorize different people right up until modern times. No obviously superior way of classifying temperament has, in fact, yet been devised. The theory of the four humours dominated medical thinking until about three hundred years ago. Many patients were still being bled even in the nineteenth century.

The Hippocratics and Greeks generally believed in positive health – health could be improved much further than the absence of illness towards well-being. Modern medicine is mainly concerned with negative health (i.e. illness), and how to restore us to health, rather than with helping us feel ‘on top of the world’. The Hippocratics were much concerned with regimen or lifestyle, both in health and disease, mainly involving the correct balance of food and exercise. The importance of exercise to both physical and mental health was recognized, and was institutionalized in gymnasia where exercise was practised on a social basis. If you had gone to Hippocrates in 400 BC (assuming you could find him) complaining of lack of energy he might have given you a detailed regimen involving an exercise programme, with a warning about too much or the wrong type of exercise; a diet, particularly including strained broths; a lot of hot and/or cold baths, and massages; some sex (if lucky); and some obscure advice about the relations between your energy and the wind direction, season of the year, etc. This would have been, in general, a reasonably effective regimen, and you would be lucky to get better advice today from your doctor.

Aristotle (384–322 BC) was a colossus of thought, straddling the end of classical Greece and Renaissance Europe. He dominated the world of the intellect, sometimes as a benign sage and other times as malevolent dictator. His thoughts were worshipped to such an extent that they circumscribed any attempts at original thought, until their eventual rejection by Renaissance Europe, when he was blamed for stifling two thousand years of thought. Much of Aristotle’s influence derives from his having been a pupil of Plato (possibly the greatest thinker ever), and then tutor to Alexander the Great (possibly the most successful conqueror of all time).

Aristotle’s views of the physiology and energies of life were derived mostly from Empedocles, Hippocrates and Plato. Nutrition, vital heat and pneuma (vital spirit) were pivotal to this view. The heart was central to the body, the origin of consciousness and the instrument of the soul, and the source of heat, pneuma, blood, and movement for the rest of the body. Pneuma was an air-like substance or spirit, containing vital heat, which was always in rapid motion, and as such was a source of both heat and motion inside the body. Pneuma was derived from air, and brought through the mouth, nose and skin to the heart, where it supplied the vital heat. A steady flow of nutrient fluid from the gut supplied the heart, and the heating of the fluid within the heart produced blood. The blood and pneuma were then distributed through vessels to the rest of the body, where the blood coagulated to form the tissues of the body under the influence of the ‘nutritive soul’. There was no circulation of blood, rather the blood was produced in the heart (and liver and spleen) and then distributed to the tissues, with no return flow. Many vessels (the arteries) were thought to be hollow (as indeed many are if the blood escapes from them after death), and were, thus, thought to carry air or pneuma through the body. The brain cooled the blood, and functioned to prevent the blood from overheating. The muscles were simply a protective layer, keeping the rest of the body warm, and had no function in movement. Nerves, as such, were unknown, as most are difficult to see; but large nerves and tendons were collectively called neura and were thought to function in movement of the limbs, by acting as cords pulling the bones. The pneuma supplied the ‘go’, energy or movement throughout the body.

Aristotle’s pneuma was also the motivating force outside the body – in the physical world. According to his mechanics, the natural state of things was rest rather than movement; so that the continuous movement of an object such as an arrow in flight required pneuma to be continuously pushing the arrow from behind. Thus we can see that pneuma was energy for Aristotle, although of course it had a rather different role in classical thinking. Aristotle was also partly responsible for the theory of the four qualities: hot, cold, wet, and dry, which were components of the four elements. Thus earth was cold and dry, water cold and wet, air hot and wet, and fire hot and dry. This became a very important doctrine in later medicine and alchemy, because it gave a key as to how to alter the ratio of the elements; thus, for example, water could be converted to air by heating, or air could be converted to fire by drying.

Aristotle was the first authority to use the term energeia, from which we derive the word ‘energy’. But he used it to mean the ‘actual’, as opposed to the ‘potential’, as he had an obscure theory that ‘change’ involved turning from a potential thing into an actual thing. So when something happens, a potential happening changes into an actual happening. Thus for Aristotle energeia was tied up with change and activity, but in what seems now a rather obscure and abstract way.

Although Aristotle’s view of physiology and energetics was most influential, it was far less original and interesting than that of Plato. Plato was not really interested in physiology, as he had his mind set on higher things, but he wanted to find a physical location for the various parts of the soul that he had identified. For, according to Plato, the body is peopled by a bickering community of souls, ruled over by a somewhat prissy head. The immortal soul is in the head, and the mortal soul located from the neck down. The courageous part of the mortal soul is found above the diaphragm, where it can both listen to reason (from the head) and subdue the lower regions. This soul’s main home is the heart; when the head thinks that the passions are out of control it informs the other organs, and the heart starts leaping with excitement and overheating. The lungs can then save the day by cooling and providing a cushion for the overtaxed heart. Below the diaphragm dwells the ‘appetitive’ soul, which while necessary for life needs to be kept chained, far from the seat of reason. This part of the soul is controlled by the liver, capable of listening to reason. The liver regulates the nether regions either by contracting to block passages causing pain and nausea, or by spreading cheerfulness and serenity to the surrounding parts of the soul. The length of the gut is intended to prevent food passing through too quickly, which would cause an insatiable appetite, and make mankind impervious to culture and philosophy. The spinal marrow is called the universal ‘seed-stuff’ (also the source of semen) fastening the soul to the body. The different kinds of soul are found in various parts of the marrow, while reason and intellect occupy the brain. This community-of-souls theory of the body shows how appealing, but empty, intentional explanations of physiology can be. In order to progress, the supernatural had to be replaced by mechanical causes and energy as the source of change.

The deaths of Aristotle and Alexander in 322 and 323 BC respectively marked the end of classical Greece. But Alexander had spread Greek culture across the known world, ushering in the age of Hellenism, which was a fusion of Greek and Persian culture. Hellenism’s most successful centre was in Alexandria, briefly flourishing under Ptolemy I. A former pupil of Aristotle, Ptolemy attracted some of the greatest Greek scientists and thinkers to Alexandria’s Museum and Library. Two brilliant physicians, Herophilus and Erasistratus, were able for the first time to practise dissection of the human body there and used this to great effect. This had been impossible previously due to the commonly held assumption that the body retained some sensitivity or residual life after death. Changing beliefs about the soul’s relation to the body enabled Herophilus and Erasistratus to dissect dead humans, and even, it has been claimed, live criminals. The result caused a revolution in anatomy: the exploration of a whole new realm below the human skin. The nerves, and their relation to the brain and muscles, were discovered. The brain was explored and the fluid-filled cavities within (ventricles) were thought to be filled with a new form of pneuma: psychical pneuma (animal spirits). This psychical or mind pneuma radiated out from the brain, through the nerves, to energize the muscles. However, Alexandrian scientific creativity gradually declined and the influence of eastern mysticism increased.

In the second and first centuries BC, Rome swept the political stage while largely adopting Greek culture and thinking. Into this new world was born Galen (AD c. 129–216), antiquity’s last great physician and biologist. An architect’s son from Pergamon, he studied philosophy then went to Alexandria to learn dissection. Returning to Pergamon, he became surgeon to a school of gladiators, where he gained invaluable experience in treating wounds. In AD 169 Galen was summoned to Rome to become personal physician to Marcus Aurelius, the Philosopher Emperor. These duties do not seem to have been too onerous as Galen continued his writing and scientific work, in the end producing over 130 books. Many are commentaries on and syntheses of previous medical knowledge, including textbooks and treatises on almost all diseases, treatments and methods of diagnosis. These books became the central texts of medicine for fifteen hundred years. Galen was seen as a kind of medical theologian, for whom anatomy was both praise and veneration of the one true God. And this, twinned with his interpretation of the body in Aristotelian terms, guaranteed the acceptance of his writings by later Christian and Islamic authorities.

Galen’s doctrine of pneuma synthesizes earlier ideas of the Hippocratics, Aristotle, the Alexandrians and Stoicism (a philosophy founded by Zeno). Pneuma can be translated as ‘airs’, and was thought to be an invisible force within the air. Pneuma was translated into Latin as spiritus, but is most naturally translated today as ‘energy’. To the Stoics, pneuma was a non-material quality or form imposed on matter. Pneuma pervaded the universe and was the vehicle of cosmic ‘sympatheia’, by which each part of the universe was sensitive to events in all others. Pneuma acted as a force field in the air, immediately propagating movement to the edge of the universe and then back again. This is reminiscent of modern concepts of sound waves or of electromagnetic waves moving through the air. Inside the body, pneuma pervaded the blood vessels and nerves and enabled the transmission of sensitivity, movement and energy.

Galen distinguished three different kinds of pneuma inside the body: natural spirit, vital spirit and animal spirit. These were produced by the three main organs and their associated faculties or souls (the idea was derived from Plato). The liver, hub of the appetitive soul and supposed source of the veins, produced natural spirits. The heart, centre of the spirited soul and source of the arteries, produced vital spirits. And the brain, home of the rational soul and source of the nerves, produced animal spirits. The liver took digested food from the stomach and guts, concocting it into dark, venous blood containing natural spirits, which when distributed to the rest of the body was assimilated forming the substance of the organs. This was the basis of the appetitive (or nutritive) faculty of the liver. Taking venous blood, the heart concocted it with pneuma, derived through the lungs from the air, producing red arterial blood, full of vital spirits. These vital spirits, distributed throughout the body by the arteries, were then responsible for all other living processes, apart from those of movement and thought. The brain transformed vital spirits into psychical spirits, which then became responsible for consciousness, and when distributed by the nerves, for muscle movement and sensation.

Pneuma is the closest we get in antiquity to the modern concept of energy. It is a non-material, potential form of motion, action and heat, and its transformations correspond to the transformations of energy. The ghost of pneuma still haunts the modern idea of energy, but has been transmuted into an altogether more pragmatic concept by today’s more materialistic scientists.

After Galen, there was little innovation in Greek and Roman science and an increasing emphasis on mysticism and theology. In the fourth century, the official religion of Rome became Christianity, at that time diametrically opposed to the scientific spirit. In the fifth century, the western half of the Empire was invaded by German tribes, ushering in the Dark Ages, which lasted almost a millennium. The eastern, Greek-speaking side of the Empire lasted much longer, gradually diminishing in power. In the seventh and eighth centuries, the Islamic Arabs conquered Syria, Egypt, North Africa and Spain, absorbing Greek knowledge. Although it was not until the eleventh century and later that Christian Europe was finally able to reabsorb Greek learning from the Arabs, and, at last, to spark the Renaissance.

Alchemy forms a bridge between the ancient Greek and Roman learning and the birth of modern science in seventeenth-century Europe. While the alchemists’ quest started two thousand years ago in Alexandria, China and India, as late as 1680 Isaac Newton still devoted most of his time to the mysterious art. Because it existed through the dark ages of knowledge and science, alchemy reflected the time’s religious, symbolic and mystical forms. But it also kept many of its practitioners in contact with classical knowledge and experimental science. The alchemists appear to modern eyes as a bunch of wacky mystics. It seems incredible that sober citizens came up with this bizarre combination of chemistry and religion. Why not engineering and sex, or poetry and gardening? However, many alchemists were intent on the very practical goals of limitless money and life everlasting. What could be more modern than that? Unfortunately for them, the theories of alchemy were completely wrong.

The importance of alchemy to our story is that it attempted at least to understand what things are made of, and much more importantly how they change. If we look at a stone or egg naïvely, it is hard to see what they consist of and where their potential for change comes from. What is it about an egg that enables it to turn into a chicken? What is it about a piece of wood allowing it to burn? What is it about a lump of gold that makes it last forever? The alchemists put all these questions into the fire. Fire was the great transformer and transmuter: separating metals, distilling essences and cooking food. In many ways the alchemist was a cook, his technology was derived from the kitchen, and he sought to transform his raw materials, through recipes, herbs, and inspiration into perfection. The alchemist also sought to isolate (by distillation and other methods) the essence or spirit of things, as a metal is isolated from ores or alcohol distilled from wines or a drug ‘purified’ from a plant. They thought adding the essence of gold (known later as the ‘philosopher’s stone’) to other metals would turn the base metals into gold. Unfortunately for the alchemists, they did not yet realize that gold was an unchangeable element, more fundamental than earth, fire, air or water and that there was no essence of gold to be given to other metals. The alchemists’ real achievement was that by their slaving over a hot stove and forging mental concepts, they slowly transformed the categories and concepts by which matter was seen, eventually enabling the evolution of chemistry and biochemistry.

What have we learnt from our journey through the scientific progress of the classical world? From Empedocles, Aristotle and the Atomists, we discovered that the world and its changes do not have to be understood in terms of the wishes and desires of gods, spirits or even matter itself. It can rather be explained in terms of the structure and interactions of a small number of basic particles or elements, each too small to see, but that when mixed together make up visible matter. The changes we see are due to forces of attraction or repulsion between these particles, leading to changes in the composition of matter. From Hippocrates and Galen, we learnt that death and disease are not due to the will of gods, devils or sorcerers, but can be explained in terms of the workings and malfunctions of the body machine. And this can be understood in terms of the body’s various solid organs with different functions, the various vital liquids that flow within and between them, and the various invisible spirits or gases that animate the body. However, this knowledge does not explain how someone moves a hand by willing it, how thought is possible, or how life differs from death. Our journey must continue into the modern world in pursuit of the energy of life.

THE ENLIGHTENMENT

Our modern world was sparked into existence by the scientists and thinkers of seventeenth and eighteenth-century Europe. Without their intervention, we could now be living very differently, perhaps in some sort of impoverished, fundamentalist state. But it required revolutions and counter-revolutions, heroes and anti-heroes, blood and tears to achieve the transformation of thought that came to be known as ‘The Enlightenment’.

It was the work of four scientists in particular that prepared the ground for this new scientific approach. Their discoveries exploded the medieval conventions of cosmology. The first scientific bombshell unleashed on an unsuspecting medieval world was the discovery that the earth was not at the centre of the Universe. Copernicus (1473– 1543) wisely did not ever openly state this while alive, but the shockwaves from his heliocentric theory rocked the medieval church nonetheless. Then, Kepler (1571–1630) showed that the planets do not move in circles, but ellipses. Furthermore, Galileo (1564–1642) used a telescope to show that all was not perfect among the ‘heavenly bodies’; the moon was pitted with craters and volcanoes, Jupiter had moons, and the blanket of the Milky Way in fact consisted of millions upon millions of stars. Isaac Newton (1642–1727) then went on to show that the planets were not a law unto themselves, but rather followed the same rules as everything on earth.

Even more fundamentally important, Kepler, Galileo, and Newton stated that everything, ranging from teapots to planets, ‘obeys’ mathematically precise, mechanical ‘laws’, conjuring up a clockwork universe, policed by cold, mechanical ‘forces’. There was no more room for spirits, gods or God. No room even for Empedocles’ forces of love and strife. Things did not move (or even stop moving) because they wanted to do so, but because they were ‘forced’. According to Newton’s (and Galileo’s) first law of motion, movement itself was no longer a sign of life or spirit. Only a change in speed or direction was an active process, and this was due to an external ‘force’. Thus, amazingly, all movement in the world, apart from that of living animals, could be explained as passive and mechanical. The non-living world suddenly became frighteningly cold, empty and dead. In place of spirits, forms and purposes, there were forces. In fact, the ‘forces’ that inhabited Newton’s universe were not so radically different from the preceding ‘spirits’. The new ‘forces’ were unexplained and inexplicable, but had an inanimate mechanical basis, as opposed to the living freedom of ‘spirits’. These forces rigorously obeyed precise, mathematical laws, whereas the spirits had followed their desires. The technological wonder of the age was the mechanical clock; this in turn became a metaphor for the Universe itself. With the invention of the clock, Time itself began to tick, and the whole Universe was forced to beat in time. But it was not only the non-living things that were forced to bow to the new mechanical spirit of the age. René Descartes (1596–1650) proposed that animals were also purely mechanical devices, automata with no feelings or consciousness. The processes of the body could be explained just using mechanical laws. Thus, for example, the nerves acted as pneumatic pipes, transmitting pressure changes of animal spirits (psychical pneuma) at the nerve endings to the brain, and from there through other nerves to the muscles, where the pressure inflated the muscles.

‘Now according as these spirits enter thus into the concavities of the brain, they pass thence into the pores of the substance, and from these pores into the nerves; where according as they enter or even as they tend to enter more or less into the one or the others, they have the power to change the shape of the muscles in which these nerves are inserted, and by this means to make all the limbs move.’

He went on to compare the nervous functions of the body and mind to the automatic puppets, then fashionable, which, driven by hydraulic pipes, could move and even seemingly speak.

Descartes did leave a small bolthole for the soul in the pineal gland, a small almond-shaped organ at the centre of the brain. He suggested the soul was radically different to matter and not subject to the laws of physics, but interacted with the body, through the animal spirits inside the pineal gland. The soul consisted of an unextended, indivisible, thinking substance, constituting the mind, all thoughts, volitions and desires. But all else on earth, including the human body and brain, was a vast clockwork mechanism.

Descartes has been much demonized as the inventor of ‘Dualism’, which purported that the world consists of two radically different substances: mind and matter. Dualism is, however, an ancient concept present in all early cultures; in Classical Greece, it is Plato’s concept of two separate worlds of appearances and perfect ideas, and in Aristotle’s substance and form; it is consistently found throughout Hindu, Jewish, Christian and Islamic thought as the separation of body and soul. Descartes did not invent Dualism. He was, on the contrary, a radical materialist, considering almost everything to consist solely of one substance, matter, but perhaps his nerve failed when it came to a denial of the soul. It is conceivable Descartes might have done this were it not for the Inquisition, which had, in 1616 and 1633, condemned Galileo for his heretical scientific beliefs.

Whether Descartes intended it or not, his and other mechanical philosophies separated body and mind even further, so that they were commonly regarded as radically different. The body and brain was seen as a cold machine and analysed in relation to the latest technical toy, which ranged across clocks, levers, hydraulic puppets, steam engines, electric robots and electronic computers. Whereas the mind became some wishy-washy, non-material thing, too slippery to analyse, and best left to theologians and philosophers to chew over. Consequently the trail to body energy and mind energy splits in two here, only rejoining relatively recently.

One of the world’s greatest philosophers, mathematicians and scientists, Descartes appears to have been intrinsically lazy. Rarely getting up before midday, he worked short hours, and read little. Where did he find the energy for his great works? One answer may lie in his lack of routine. He had no need of a job, as after selling his father’s estates he lived off his investments. So he immersed himself in his studies and whenever boredom threatened he joined an army – trying out those of France, Holland and Bavaria. He was sociable, but when friends distracted him from his conceptual tasks, he moved away. Descartes never married, and his only natural child died at five, so there was never any need to adapt to a domestic routine. He was capable of short bursts of extreme concentration. On a cold morning of the winter of 1619–20 when he was with the Bavarian army, Descartes climbed into a large oven to keep warm. He stayed in there all day thinking, and when he eventually emerged had half completed his critical philosophy, which then became the foundation of modern philosophy. This anecdote stresses the importance of removing all external distractions to intense thought. But Descartes would never have managed this feat without also removing the further internal distractions of routine thoughts, feelings and desires. And, most importantly, he would never have got anywhere without supreme self-confidence. Only powered by optimistic egotism could he reject all previous thinking, rebuilding the conceptual map of the world. Confidence is the sine qua non of creativity. Descartes’ power finally gave out when lured to Sweden by Queen Christina, he was impelled to give her daily lessons at five in the morning. This proved too much for his weak constitution and he was dead within six months.

Although Descartes tried, he didn’t succeed in his application of the new mechanical approach to biology. But, in the hands and mind of William Harvey (1578–1657), this approach yielded a remarkable success with his discovery of the circulation of the blood. Blood had been thought made in the liver and heart, passing directly from the left to right sides of the heart, and then out to the rest of the body, never returning to the heart; although it might ebb and flow in the same vessels. The heart’s beat was thought due partly to breathing and partly to the formation of heat and spirits inside the heart. Thus the heart was not thought to pump the blood. Harvey showed by experiment and quantitative argument that it received as much blood as it pumped out. It was not making blood but circulating it. The heart was not an alchemist, but a mechanical pump. Furthermore, Harvey proved it was a double pump: veins brought blood from the rest of the body to the right side of the heart, which pumped the blood to the lungs; it returned from there to the left side of the heart, then was pumped to the rest of the body, through the arteries. It is telling that the function of the heart and vessels was elucidated by the use of a mechanical analogy, inspired by a pump and pipes for circulating water.

There was one glaring hole in Harvey’s scheme. He could not see how the blood got from the arteries, through the organs and back to the veins. This was because the vessels involved, the capillaries, were too small for Harvey to see. So it was left to Marcello Malpighi (1628–94) to complete our image of the circulation by finding the capillaries using the newly discovered microscope. The microscope opened up a new miniature world to discovery, just as the telescope had laid bare the heavens, and the dissecting knife had opened the body beneath the skin. The first users of the microscope must have experienced the thrill of entering unknown territory. Malpighi described for the first time the structure of the lungs, spleen, kidneys, liver and skin. Many features of the human body still bear his name (such as the Malpighian tubes of the kidney), just as the explorers of sea and land left their names on the Americas. Antoni van Leeuwenhoek (1632–1723), a Dutch draper and pioneer microscopist, discovered striped muscle, sperm, and bacteria. And then it was the English scientist Robert Hooke (1635–1703) who first saw and named ‘cells’, but failed to recognize their significance.

Comprehension of the microscopic structure of living things is essential to any understanding of how they work. In this respect they differ from mechanical machines, which are constructed on a macroscopic level from components that at a microscopic level are both homogenous and uninteresting. By contrast, living things appearing to the naked eye as fairly simple, reveal mindboggling complexity at a microscopic scale. This vertiginous intricacy continues down to the atomic scale. Both the mechanical biologists, and all previous generations of biologists were, of course, completely unaware of this vital piece of knowledge. Some biological functions (such as how the blood circulates) are understandable at the macroscopic level but the most important secrets (such as why the blood circulates) are located on a molecular scale, beyond the reach of even the microscopists. So, mechanical biologists made relatively little progress, despite their occasional breakthroughs with the circulation of the blood and the optics of the eye.

In reaction to the mechanical (and chemical) explanations of life proposed in the seventeenth century, many scientists and thinkers defended life as radically different from the non-living, due to the possession of a ‘vital force’. One such vitalist was Georg Ernst Stahl (1660–1734), who explained life and disease as the actions of a sensitive soul or ‘anima’, inhabiting every part of the organism preventing its decay. This ‘animism’ was an example of ‘vitalism’, the belief that life was not explicable in purely mechanical and chemical terms, harking back to Aristotle and earlier. Stahl was also a chemist, and proposed the infamous phlogiston theory. This theory interpreted combustion, i.e. burning with its accompanying flame and heat, as due to the release of a special substance called phlogiston, a stored heat energy. Stahl believed that plants took phlogiston from the air, and incorporated it into their matter, so if the plant was then burnt (as wood or straw) the phlogiston could escape into the atmosphere again. Or if, alternatively, the plants were eaten by animals, phlogiston could be released by the animal’s respiration, a kind of combustion inside the body. The phantom of phlogiston beguiled chemists for about 100 years until finally extinguished by Lavoisier, who also disproved Stahl’s vitalism. However, Stahl had already died in a state of severe depression long before the demise of his theories.

This historical journey has led us to a cold and abstract world of science, stripped bare of gods and spirits, ruled instead by laws and forces. We have ventured below the skin of appearances, and must travel inwards to ever smaller scales if we are to penetrate the meaning of life. The human body has become a machine, to be taken apart piece by piece. But the next veil of mystery which hides the secret of life is not a physical or mechanical one. The old dream of the alchemists is suddenly to bear fruit in the form of the chemistry of life.

THE REVOLUTION

Human attempts to find the secret to the energy of life had stalled for a thousand years but now were finally beginning to make some progress. This was due to the startling achievements of one man: Antoine Laurent Lavoisier (1743–1794), creator of the Chemical Revolution and victim of the French Revolution. Aristotle, Galen, Paracelsus, Stahl and others had all recognized that there was some relation between breathing, heat and life but the nature of this relation was no longer clear. Harvey had shown that blood circulated from the lungs to the rest of the body and back again, via the heart, but why did it circulate in this way? Was it bringing something to or removing from the tissues? The analogy between life and combustion had been noted, but combustion was seen as a kind of decomposition, so its relevance to life was still unclear.

Several British scientists had shed light on these mysteries. Robert Boyle (1627–1691) discovered an animal could not survive long in a jar after the air was removed by a vacuum pump, suggesting animal life is dependent on air or on some component of air. Boyle’s assistant, Robert Hooke (1635–1703) showed that the mechanical movement of the chest in breathing was inessential to life, since he was able to stop the chest moving in animals while maintaining life by blowing air in and out with bellows. Richard Lower (1631–1691), a pioneer of blood transfusions, showed that the colour change in blood from blue-black in the veins to red in the arteries occurred as it passed through the lungs.

Incredibly, some seventeenth-century scientists believed that life was powered by something akin to gunpowder. The invention of gunpowder in the late middle ages had led to the belief that its components (sulphur and nitre) were also responsible for thunderstorms, volcanoes and earthquakes. This supposition was apparently confirmed by the sulphurous smell of volcanoes and thunderstorms. Lightning was thought to result from a nitre-like component of air, the nitrous spirit. It was proposed that this nitrous spirit was extracted from the air by the breathing body, then combining with sulphurous compounds already contained in the body to produce a combustion – the explosion of life. The gunpowder theory of life is another fascinating example of how technological change provided new analogies and innovative ways of thinking about biology.

Between 1750 and 1775, the main gases were discovered by British chemists: carbon dioxide by Joseph Black in 1757; hydrogen by Henry Cavendish in 1766; nitrogen by Daniel Rutherford in 1772; and oxygen independently by Joseph Priestley in 1774 and the Swedish chemist Karl Scheele in 1772. However, these gases were not considered distinct chemical substances, but rather, types of air, as Empedocles’ four elements theory still held sway – 2,200 years after his death. So, for example, carbon dioxide was known as fixed air, and oxygen as dephlogistonated or fire air. But the scientific stage was set for a revolution: the overthrow of the four elements, the extinction of phlogiston, the rejection of vitalism, and for the creation of chemistry and physiological chemistry.

Lavoisier was an unlikely revolutionary: his father was a lawyer and his family was part of the prosperous French bourgeoisie. He received the best possible education and studied law, gaining an interest in chemistry from a family friend. The French Academy of Sciences had been in existence since 1666, and at only 21, Lavoisier decided he wanted to be a member. He successfully investigated various methods of public street lighting, and was awarded a gold medal by the king and at just 25 was elected to the Academy. He then embarked on the series of chemical experiments that was to reshape the world of science. But, like most other contemporary scientists, he had to finance his own experiments, so he used his maternal inheritance to purchase membership of a tax-collecting firm. While this provided him with financial security, it was to eventually prove fatal, as tax collectors were not popular at all after the French Revolution. His career did, however, also provide him with an introduction to his thirteen-year-old future wife, Marie, the daughter of another tax collector. This turned out to be a wise move, as Marie rapidly became a proficient scientist herself, serving as an able assistant to all Lavoisier’s works.

In 1775 Lavoisier was appointed scientific director of the Royal Gunpowder Administration, and started working on methods of improving the production of gunpowder and on the general nature of combustion, oxygen and respiration. When he finally disproved the phlogiston theory, the Lavoisiers staged a celebration in which Marie dressed as a priestess, burning the writings of Stahl on an altar. But 1789, the year of publication of Lavoisier’s great work Traité élémentaire de chimie, also marked the start of the French Revolution. Although he served in the revolutionary administration, his bourgeois and tax-collecting credentials finally told against him, and he was imprisoned during the Reign of Terror. Marie was given the chance to plead for his life, but chose to energetically denounce the regime instead. Lavoisier was tried and guillotined in 1794.

Lavoisier’s first target was the theory of the four elements. Alchemists had found that boiling water for a long time resulted in the disappearance of water and appearance of a solid residue. They thought this resulted from the transmutation of one element – water – into another – earth – by the action of heat or drying. We now know the solid residue is derived partly from salts dissolved in impure water and partly from the container in which the water is boiled. Lavoisier showed this by boiling purified water in a sealed glass container for one hundred and one days. He found that a small amount of solid matter appeared in the water but by weighing the matter, water and container demonstrated that all this matter was derived only from the container, thus proving water could not be transmuted into earth.

Lavoisier next turned his attention to the burning of metals. Heating metals results in a rusting of the surface, which had been compared to combustion. But according to phlogiston theory (equating phlogiston with the element of fire) combustion results from the release of phlogiston from the material into the air, and should thus result in a decrease in weight of the remaining material. Lavoisier tested this by measuring the weight of the metal before and after heating. He found that the metal always gained weight after heating; and furthermore, part of the air around the metal disappeared after the heating. Thus, the phlogiston theory of metal combustion could not be correct: Lavoisier interpreted his findings to mean that during the heating of the metal, some of the air combined with the metal to form rust, thus increasing the weight of the metal. But what was it in air that combined with the metal?

At this point (October 1774) Joseph Priestley visited Paris, dining with Lavoisier and other French scientists. This crucial meeting was to provide the essential key to Lavoisier’s research, but also resulted in the two scientists’ long-running, bitter dispute over scientific priority and plagiarism. Priestley (1733–1804) was a Presbyterian minister from Yorkshire who developed a surprising bent for science. While investigating the properties of carbon dioxide, derived from the brewery next door, Priestley discovered that when the gas was dissolved in water, it produced a pleasant drink (soda water, present in most soft drinks today). He received a prestigious medal from the Royal Society for this invention and was subsequently recruited by the Earl of Shelburne to be his secretary and resident intellectual. Priestley set up a laboratory at Shelburne’s country estate and proceeded to isolate a number of gases. In August 1774, Priestley first isolated oxygen by collecting the gas resulting from heating mercuric oxide. He found a candle burned more brightly and a mouse survived longer in a jar of this gas than in ordinary air. Priestley considered the new gas to be a variety of air (‘pure air’) and adhering to the phlogiston theory, later named it ‘dephlogisticated air’. At this crucial point Shelburne took Priestley to Paris and at a fateful dinner with Lavoisier, Priestley told of his recent experiments. Whether or not this meeting was the inspiration for Lavoisier’s subsequent experiments was later hotly disputed. But Lavoisier immediately repeated Priestley’s experiment of producing oxygen by heating mercuric oxide, realizing that this new gas must be the substance in air combining with the heated metal to produce rust (metal oxides). But Lavoisier interpreted the new gas as a separate substance (or element), not a variety of air, and later named it ‘Oxygen’ – which is Greek for ‘acid former’, because he believed (wrongly) that all acids contained some oxygen. In April 1775, Lavoisier presented his findings at the French Academy without reference to Priestley, claiming he had independently discovered oxygen. Priestley subsequently disputed his priority in the discovery of oxygen. There now seems little doubt that Priestley and Scheele discovered oxygen, but because they used the phlogiston theory and only had a crude conception of chemical elements, they failed to interpret their findings as a new substance.

Another bitter dispute followed over the composition of water. Water was still regarded as an element, but Priestley, Cavendish and James Watt (famous for his discovery of the steam engine) had found that if a mixture of hydrogen and oxygen (or air containing oxygen) was ignited with a spark, then water was produced. They were, however, slow to publish their findings. An assistant of Cavendish visited Paris in 1783, innocently telling Lavoisier of their findings on the production of water from hydrogen and oxygen. Lavoisier immediately returned to the laboratory repeating the experiment, and went even further by reversing it; he heated steam to produce oxygen and hydrogen. He swiftly published the result, claiming priority for the discovery. This understandably caused a furore. But the important knowledge was that water was not, as previously thought, an element, but a combination of oxygen and ‘hydrogen’ (another name coined by Lavoisier, meaning ‘generator of water’). At last the four elements theory was falling apart and something had to take its place. Lavoisier provided that new system, essentially modern chemistry, according to which there are many elements, including oxygen, hydrogen, nitrogen, carbon and phosphorus, which can combine in various ways to produce compounds, which depending on their nature and conditions may be either solids, liquids, or gases.

Lavoisier’s key contribution here was to accurately measure the change in weight and to use the principle of conservation of mass – the idea that regardless of what you do to an object it will not change in weight (as long as no mass escapes). Before Lavoisier’s breakthroughs it was not clear whether matter could appear or disappear during reaction or transformations. Lavoisier showed by weighing that the mass stayed the same during a reaction, and explicitly stated the principle of Conservation of Matter: matter could not be created or destroyed. He used this principle to track where the matter was going in a whole series of reactions. Because of Lavoisier’s principle, contemporary improvements in weighing techniques contributed to the development of chemistry, as much as the microscope contributed to biology. He also provided a nomenclature for chemicals, still in use today. All these changes amounted to a Scientific Revolution, which transformed alchemy into chemistry. The new system was rapidly adopted throughout Europe, only rejected by a few die-hard phlogiston theorists, including perhaps unsurprisingly, Priestley. There was no love lost between these two great scientists. Priestley, the experimentalist, regarded Lavoisier’s theories as flights of fancy; while Lavoisier, the theoretician, characterized Priestley’s investigations as ‘a fabric woven of experiments hardly interrupted by any reasoning’.

Priestley moved to Birmingham in 1780 and joined the Lunar Society, an influential association of inventors and scientists including James Watt, Matthew Boulton, Josiah Wedgwood (engineer and pottery manufacturer), and Erasmus Darwin (poet, naturalist and grandfather of Charles). In 1791 Priestley’s chapel and house were sacked by a mob angered at his support for the French Revolution. He fled to London, and then, in 1794 at sixty-one, emigrated to America, settling in Pennsylvania, and becoming one of the New World’s first significant scientists.

Lavoisier then teamed up with Pierre-Simon de Laplace, one of the greatest mathematicians in France. They wanted to investigate the relation between combustion and respiration. Combustion is the process of burning, usually accompanied by flame, such as the burning of a candle. Respiration had originally described breathing, but it had been discovered that this process was associated with the consumption of oxygen and production of carbon dioxide; ‘respiration’ thus came to stand for this process of gas exchange by organisms. Both combustion and respiration consumed oxygen from the air, replacing it with carbon dioxide and both produced heat. But could the conversion of oxygen to carbon dioxide by a living animal quantitatively account for all its heat production? In other words, was respiration really combustion, accounting for the heat produced by animals? They decided to compare the heat and carbon dioxide production of a respiring guinea pig and of burning charcoal (pure carbon). Lavoisier and Laplace invented a sensitive device to measure heat production, although it only worked well on days when the temperature was close to freezing. When, at last, everything was working, they found the burning of charcoal and the guinea pig’s respiration produced the same amount of heat for a given amount of carbon dioxide. They concluded therefore that the heat production of animal respiration was due to combustion of carbon (from food) within the animal, and that respiration was in fact slow combustion. From this result they had the audacity to claim that a vital living process was in fact a simple chemical reaction. And they were right – well, partly.

Priestley had again been working on similar lines. He had shown that candles and mice lasted approximately five times longer in a jar of oxygen than in a jar of ordinary air. This is because ordinary air consists of one fifth oxygen and four fifths nitrogen, a gas which does not support life. Priestley said of oxgyen (or rather, as he called it, dephlogisticated air):

‘It is the ingredient in the atmospheric air that enables it to support combustion and animal life. By means of it most intense heat may be produced; and in the purest of it animals may live nearly five times as long as in an equal quantity of atmospheric air. In respiration part of this air, passing the membranes of the lungs, unites with the blood and imparts to it its florid colour, while the remainder, uniting with phlogiston exhaled from venous blood, forms mixed air.’

But if all the animals of the world are continually consuming large amounts of oxygen, why doesn’t the oxygen in the atmosphere run out, as it does in the jar? Priestley discovered that plants produced large amounts of oxygen when a light was shone on them, and went on to suggest that all the oxygen used by the animals of the world is produced by plants. This suggestion is more or less correct, although the photosynthetic bacteria and algae of the sea (also now classified as plants) contribute as well to the production of oxygen, and it would take over two thousand years for the atmospheric oxygen to run out if all plants stopped producing oxygen. So both the food we eat and the oxygen we breathe come ultimately from plants; this means all energy is derived from plants, who in turn get their energy from the sun.

But if animal respiration was a type of combustion, where within the animal did it occur? Lavoisier and Laplace believed it happened in the lungs. They thought that carbon (and hydrogen) derived from food was brought to the lungs by the blood, and was burnt there with the breathed-in oxygen to produce the waste products of carbon dioxide (and water) then breathed out; and heat, which was absorbed by the blood and distributed to the rest of the body. Their belief that respiration was the combustion of food using oxygen was correct, but they were wrong in thinking that this combustion occurred in the lungs. Their view prevailed for fifty years, although Lagrange, the famous French mathematician, argued that the combustion could not occur solely in the lungs because if all the heat were released there they would be burnt to a cinder. He postulated that oxygen was taken up by the blood and the combustion of food occurred within the blood. This theory was very influential and competed with that of Lavoisier and Laplace. But in 1850, it was found that a frog muscle, separated from the body, still takes up oxygen liberating carbon dioxide; subsequently it was shown that the liver, kidneys, brain and all the body’s other tissues do the same. In the 1870s, the role of blood was demonstrated to be solely the transport of oxygen from the lungs to the tissues, where respiration occurred within the cells, the blood then carrying back the carbon dioxide generated to the lungs. The colour change of blood, from blue-back to red on passing through the lungs, was due to a single component of blood, haemoglobin, which picked up oxygen. Haemoglobin carried oxygen in the blood: it picked up oxygen in the lungs (changing from blue to red), then carried it to the tissues, where it released the oxygen (changing back from red to blue). Thus respiration (or combustion) was occurring not in the lungs but all over the body.

But it was still not clear what relations, if any, respiration and its associated heat production had to life and its processes such as movement, work and thinking. Lavoisier and Séguin, a co-worker, had shown (using Séguin as the experimental subject) that respiration increased during work, after a meal, in the cold, and in deep thought. Thus, there appeared to be a relation between respiration and physiological work, but it was hard to imagine how oxygen consumption or heat production could cause the movement of an arm, let alone the thinking of great thoughts. To bridge that conceptual gap required the imagining of something entirely new, and that something was ‘energy’.

THE VITAL FORCE

The collapse of the four elements theory opened up a cornucopia of matter. If ‘air’ was a mixture of different gases, ‘water’ was a combination of hydrogen and oxygen and ‘fire’ was not an element at all, then what on earth was ‘earth’? The science of chemistry, newly constituted and emboldened at the start of the nineteenth century, was salivating at the prospect of dividing ‘earth’ into thousands of different ‘species’. The concept of species and family had been successfully used by Linnaeus in the eighteenth century to bring order to biological taxonomy, but what were the building blocks of matter and how were they to be classified?

The theory of the elements was recast by Lavoisier, so that there were at least thirty different elements (now known to be about a hundred), existing as elementary, indivisible ‘atoms’ (proposed by Dalton in 1808) and combined in fixed ratios to form more or less stable ‘molecules’. Chemists divided their task between the analysis of inorganic and organic (or ‘organized’) matter, the latter being the constituents or products of living organisms. The alchemists had treated organic matter as if it were a single substance or a small number of elements, for example they had treated distillates of egg or urine as single substances. The chemists set about analysing the many components of egg and urine, using new methods of organic analysis. Lavoisier had pioneered such analysis by burning organic compounds in jars of oxygen and collecting the carbon as carbon dioxide and hydrogen as water. By quantifying the amount of carbon (C), hydrogen (H), and oxygen (O), a formula of the compound could now be written down; starch was, for example, thought to be C₁₂H₁₀O₁₀. This formula was mistaken, and arose from the misconception that water was HO rather than H₂O. But these methods were rapidly improved and applied with great enthusiasm by several German chemists, in particular Liebig and Wöhler. In 1835, Wöhler wrote: ‘Organic chemistry appears to me like a primeval forest of the tropics, full of the most remarkable things’. These first optimistic biological chemists did not, however, comprehend the full complexity and extent of their new field. It is now thought that there may be roughly five million different organic compounds in the human body and these compounds may be organized in an almost infinite number of different ways.

Nineteenth-century Germany, although not yet united, had become the major centre for scientific and technological innovation. Perhaps partly in reaction to the rise of science and industrialism, the Romantic movement developed in late-eighteenth-century Germany producing a scientific philosophy known as Naturphilosophie. This bizarre hybrid of Romantic philosophy and science contributed to a resurgence of interest in the vital force and the relationships between all forces.

Justus von Liebig (1803–1873) dominated German chemistry and biochemistry in the nineteenth century, sometimes to the detriment of biology. The son of a dealer in drugs, dyes, oils, and chemicals, von Liebig gained an interest in chemistry assisting his father. But he did badly at school and was derided when he suggested a career as a chemist. He learned to make explosives from a travelling entertainer, terminating an apprenticeship in pharmacy when he accidentally blew up the shop. His father packed him off to university to study chemistry but he was soon arrested and sent home after becoming too involved in student politics. Somehow he eventually earned his doctorate and went to work in Paris with one of the best French chemists of the time, Joseph Gay-Lussac. In the 1820s he took a position at a small German university at Giessen, and over the next twenty-five years produced a veritable mountain of chemical data.

However, von Liebig did not produce this data himself, rather he invented the research group as a quasi-industrial means of producing scientific results. Taking over an unused barracks as a chemical laboratory, he staffed it with junior scientists as lieutenants, students as foot soldiers and with himself as the distant but all-powerful general. This model of the research group was so successful in producing the large volumes of research required in the industrial world that it was widely adopted and remains the main means of producing scientific research today. This is in strong contrast to the pre-industrial system of the individual scientist thinking up experiments and carrying them out himself, with or without assistance. Von Liebig was both arrogant and argumentative and had a number of angry disputes with other scientists. His success gave him considerable power, through his control over scientific journals, appointments, and societies. The parallels with science today are unavoidable. It is dominated by a relatively small number of politicians of science who control the boards of scientific societies, journals, conferences, grant-giving bodies, and appointment boards. Success in a scientific career still depends to a certain degree on gaining the patronage of these politician-scientists.

Von Liebig started the prodigious task of analysing the millions of different combinations of elements – molecules – that make up a human being. Some kind of order was brought to this chaos by distinguishing three main types of molecule: carbohydrates, fats, and proteins. At first it was thought that these ‘organic’ molecules could only be produced by living organisms, using some kind of vital force. But in 1828 Friedrich Wöhler, a friend and colleague of von Liebig, found that he could chemically synthesize urea (an important component of urine) without any living processes being involved. Ultimately, this would lead to the melting of the boundary between the living and the non-living, but not yet.

Although von Liebig showed that living organisms were constructed from a large number of organic chemicals, he believed that a ‘vital force’ was required to prevent these complex chemicals from spontaneously breaking down. He came to this conclusion because, in the absence of life, they did tend to break down, either by oxidation (combination with oxygen as in burning), putrefaction (as in flesh after death), or fermentation (conversion of sugar to alcohol). Von Liebig’s concept of vital force was similar to that of a physical force such as gravity or the electric force, but was only present in living organisms. Within the living body, this vital force opposed the action of the chemical forces (causing oxidation, putrefaction and fermentation), thus preventing the decay of the body so evident after death. Von Liebig also claimed that the vital force caused muscle contraction because he thought there could be no other way to account for the control of muscle by mind. When a muscle contracted, some of the vital force was used up to power the contraction. Consequently, immediately after the contraction, there was less vital force to oppose the decay (oxidation) of chemicals in the muscle, which therefore speeded up with an associated increase in respiration. The vital force acted as a brake on the chemical forces and when it was consumed by muscle contraction, the chemical forces speeded up. This is akin to the famous story of Peter, the little Dutch boy, sticking his finger in the leaking dam, trying to prevent the sea washing away the fields and town (just as the vital force prevented the chemical forces from eroding the body). This erroneous interpretation was used to explain Lavoisier and Séguin’s important discovery that respiration (the process of consuming oxygen to produce carbon dioxide and heat) greatly increased when a human or animal was working or exercising. Although von Liebig’s conception of the vital force was a form of vitalism, in the tradition of Aristotle, Paracelsus, and Stahl, the concept was more mechanistic in its appeal to Newtonian forces and foreshadows the concept of energy, formulated in the mid-nineteenth century.

Von Liebig’s belief that everything could be explained by chemistry and the vital force was opposed by Theodor Schwann (1810–1882). This clash proved catastrophic for the sensitive and as yet unestablished Schwann. Schwann’s productive work lasted just four years (1834– 1838), while he was still only in his twenties, but it was enough to spark a reorganization of biology almost as fundamental as that of Lavoisier’s of chemistry. Schwann’s first venture was to isolate a muscle from a frog and measure the force produced by the contracting muscle when it was held at different lengths or pulled against different weights. He found the muscle contracted with the greatest force when it was at the length that it was naturally found in the body. These experiments were seen as sensational in Germany, because for the very first time a vital process supposedly mediated by a vital force was treated and quantified in the same way as an ordinary physical force. It was now possible to give a physical account of vital processes, or reduce them to physical forces. This approach, however, did not please von Liebig and other champions of the vital force. Indeed Mayer later used Schwann’s experiment specifically to disprove von Liebig’s account of muscle contraction.

Schwann’s next achievement was the isolation of an enzyme which he called pepsin from the digestive juices. An enzyme is a biological substance present in small quantities which promotes a chemical reaction without being itself converted by the reaction. But ‘enzyme’ is a twentieth-century notion, in the nineteenth century they were known as ‘ferments’. For the alchemists, a ferment was a small quantity of active substance which when added to a passive substance could transform it into an active one similar to the ferment. For example, fire was the ferment converting flammable substances into flame and the philosopher’s stone was the ferment transmuting base metals into gold. Fermentation is the process responsible for the leavening of dough producing bread and for converting grapes into alcohol, making wine. This apparently magical transformation had been recognized since antiquity, but how exactly this happened was unclear, although it was known to require a ferment – yeast. Having discovered a ferment in digestive juice, Schwann concluded that digestion was a kind of fermentation. Von Liebig and the other chemists considered digestion, on the other hand, as a purely chemical process due to the action of acids on food. So when Schwann published his findings in von Liebig’s journal, von Liebig added a rather sceptical note to his paper.

Schwann then turned his attention to the nature of fermentation itself: one of the central scientific and technological problems of the nineteenth century. Von Liebig and the chemists believed fermentation was purely chemical and did not involve any biological organisms or processes. Schwann and two other researchers independently discovered that fermentation was a biological process caused by a fungus – yeast – the cells of which could be viewed through a microscope and could be destroyed by boiling. Schwann also showed that the putrefaction of meat was biologically mediated too, it could be slowed by heating and sealing the meat. These biological breakthroughs incensed the chemists who soon got their revenge. In the meantime, Schwann embarked on a microscopic study of the role of cells in animal development and in biology generally. The resulting ‘cell theory’ published in 1839 revolutionized how the body was viewed.

Since the theory of the four humours, the important components of the body had been thought to be the fluids and airs: the blood, phlegm, bile, urine, semen, cerebral-spinal fluid and pneuma. The important locations inside the body were the cavities (of heart, lungs, brain, guts, and blood vessels) where life was manifested in the turbulent motions of fluids and airs. The solid parts of the body (the ‘flesh’) were regarded as largely structural, perhaps because their very solidity and lack of motion argued against any involvement in change; therefore it was hard to conceive how they might be involved in the vital processes. Schwann changed all that, showing that the tissues were composed of cells and it was within the cells that most vital processes were generated. The cells were not static structures: they had a life of their own. They grew, reproduced, changed into different forms and died. Most importantly the power to cause change was located within the cells themselves, not their surroundings. Schwann called this power ‘metabolism’, from the Greek word for change. This ‘intracellular metabolism’ was responsible for fermentation by yeast and for respiration and heat production by all cells. If the secrets of life and energy were to be found, science would now have to follow the trail into the cell rather than pursuing phantom airs and vital forces. And this would require entirely new concepts and methods.

Cells were first seen by Robert Hooke in the early days of microscopes. But Hooke had only seen the large woody cells of plants. It was much harder to see animal cells, because they were smaller and their walls (membranes) were almost invisible. So the structure of animal tissue was unclear, and it had mostly been described in terms of fibres and ‘globules’ of unknown function. Schwann benefited from a great improvement in microscope optics, using this to show that not only were cells everywhere in the body, but that they were the body’s organizing principle. All cells in the body were derived from embryonic cells which divided and differentiated to form the hundreds of different types of cell making up the organism. If there was a vital principle in the body, Schwann believed that it had to be located in the cells, because all the essential processes, such as reproduction, growth, and respiration, were located in individual cells. Doubting the possibility of a vital force, Schwann thought all the properties of cells could be explained in terms of physical and chemical forces. He also believed that living processes within cells could be explained in terms of the physical structures and movements of the molecules. This was an important and influential insight which foreshadowed the spectacular explosion of cellular and molecular biology in the twentieth century. Though intensely religious, Schwann argued persuasively that the concept of a vital force was completely unnecessary, denying God’s achievement in originally producing the Universe and its physical forces: these were all that was necessary to create life.

Schwann did not have the whole answer to how cells created life, but he had found important clues in his notion of ‘metabolism’ and his discovery that digestion was partly due to pepsin. Pepsin was thought to be a ‘ferment’, but at the end of the nineteenth century it was found that ferments consisted of single biological molecules, now called ‘enzymes’. Enzymes are the magic molecules inside cells that actually cause the ‘change’ of metabolism. Enzymes are made from protein. They act on the chemicals and structures inside and outside the cell changing them from one form to another. For example, pepsin cuts other proteins into pieces without itself being cut up. Each type of enzyme can cause only one type of change but there are roughly 10,000 different types of enzyme in a cell. These enzymes are the alchemists of the cell. But each enzyme molecule can be regarded as a minute, exquisitely designed, molecular machine. Machines, because they are designed structures, performing specific tasks and transforming things by physically interacting with them; and molecular, because they consist of single molecules. Enzymes and the other molecular machines of the cell are the engines of life.

Enzymes were first discovered within yeast, as the word itself reflects – ‘enzyme’ means ‘in yeast’. Although Schwann and others had shown that fermentation was caused by yeast cells, this discovery was ridiculed by von Liebig and the chemists and replaced by von Liebig’s own nebulous chemical theory. So, the biological theory of fermentation (that it is caused by living cells rather than dead chemicals) had to be re-established later in the century by Louis Pasteur. Pasteur was unable, however, to isolate from yeast cells a ‘ferment’ which could cause the fermentation of grape juice into alcohol, in the absence of live cells. Thus it was unclear whether fermentation was a truly vital process, only occurring within living cells. This was crucial because if the sub-processes of life such as the transformation of chemicals, could not occur in isolation from a living cell, then this implied that there was indeed some vital force involved. In more practical terms, it also meant that science would never penetrate far into the cell, because the individual processes could not be studied in isolation. It was left to Buchner at the very end of the century to at last successfully grind up yeast cells, and isolate something (a bunch of enzymes) that could cause fermentation in the absence of living yeast cells. It is this event that marks the true beginning of Biochemistry, in part because it destroyed the concept of the vital force, but mainly because science had finally broken into the cell and was able to study the processes of life at the molecular level.

Schwann had opposed von Liebig and the other chemists’ views on virtually everything: the role of biology rather than chemistry in digestion, fermentation, putrefaction, metabolism, tissue structure, muscle function and the vital force. The chemists, clearly rattled by this upstart, went onto the attack, writing a satirical article on the views of the ‘biologists’ on fermentation. This article, drafted by Wöhler and made more vitriolic by von Liebig, ridiculed the cell theory of Schwann and others, scathingly describing it in terms of anthropomorphized cells shaped like distilling flasks with big mouths and stomachs, gulping down grape juice and belching out gases and alcohol. Schwann’s credibility was destroyed, he lost his job and was prevented from obtaining another academic post in Germany. He escaped into exile in Belgium, with a post in the Catholic University of Louvain, where his time was filled teaching anatomy. He never did any significant biological research again, keeping his head well below the parapet, and the chemists held the field once again in Germany. However, the experiments and book Schwann had produced in his four years of active research proved immensely influential, eventually leading to the demise of von Liebig’s ascendancy and the transformation of biology. Von Liebig publicly battled on against Pasteur, but after thirty years of denial eventually had to admit that he had been mistaken about the biological basis of fermentation. The stresses of the struggle and eventual defeat may well have contributed to his death soon afterwards. The idea of the vital force died with him, later to be reborn in the transmuted form of ‘Energy’.

We have now learnt our ‘chemistry’. We know life is not created by spirits sucked in from the air to push and pull the body’s levers; but rather an element of air, oxygen, is combined with molecules of food within the cells of the body, producing something then able to animate our bodies and minds. The stage is now set for the discovery of energy itself.

THE BIRTH OF ENERGY

The modern scientific concept of energy was an invention of the mid-nineteenth century. ‘Energy’ is a child of the industrial revolution: its father a thrusting steam engine; its mother, the human body itself, in all its gory physicality; and its ancestors the ethereal spirits of breath and air. The evolution of this concept was aided by an eclectic group of engineers, physicians, mathematicians, physiologists and physicists, with a strong supporting cast of soldiers, sailors and, inevitably, accountants. Today, the scientific concept of energy has a harsh façade of cold forces and austere maths, but its core is much softer and more appealing, reflecting its biological origins in vital forces and wild spirits.

The physical heritage of energy begins with Watt’s invention of the steam engine in the eighteenth century. A steam engine produces work (movement against a force) from heat, something never before possible. The question is how? Is heat somehow converted into work or does the flow of heat from hot to cold drive work as the flow of water in a stream drives a water-mill? Sadi Carnot (1796–1832) thought the latter was true but was only half right. Carnot’s father was a Minister of War in Napoleon’s government and Sadi fought in the defence of Paris in 1814. The total defeat of Napoleon’s armies and France’s ignoble subjugation turned Carnot’s thoughts towards one source of England’s growing power: James Watt’s steam engine. The engine seemed to promise limitless power derived from hot air and steam alone but the elaborate contraptions of the early nineteenth century did not always deliver what was promised. Carnot wanted to improve the efficiency of steam engines but there was still no good theory of how they actually worked. So Carnot produced one, based on Lavoisier’s conception of heat. Lavoisier had disposed of the phlogiston theory of combustion but had replaced it with something rather similar: the caloric theory of heat. According to Lavoisier, heat was a substance, a massless fluid called ‘caloric’, which he considered one of the elements, like oxygen or phosphorus. This caloric theory was mistaken but its legacy still remains in our unit of heat energy: the ‘calorie’. Carnot thought if heat was an indestructible fluid, then steam engines must be driven by the flow of heat from a hot source (the boiler) to a cold sink (the condenser), just as a mill-wheel is impelled by the flow of water. His important insight was that there had to be a large temperature difference to cause the heat to flow and that there was a quantitative relation between this heat flow and the power output of the engine, which could then be used to predict the efficiency of conversion of coal into work.

Carnot’s theory was, however, based on Lavoisier’s mistake, that heat was an indestructible substance or element. This mistake was revealed by James Joule (1818–1889), a rich brewer from Manchester. In the brewery workshops, Joule measured the heat produced by passing electricity through water. His results showed electricity was being converted into heat, which was impossible if heat and electricity were two indestructible fluids. The fellows of the Royal Society were unimpressed by his findings, so Joule went back to the workshop and started meticulously measuring the small amount of heat generated by turning paddles in water. From these experiments it appeared that work could be quantitatively converted into heat. The cautious Royal Society again rejected Joule’s findings as impossible. Joule became so obsessed with proving his case that when on honeymoon in Switzerland, ignoring the romantic situation and scenery, he spent much of the time dragging his wife up and down a waterfall, trying to measure the temperature difference of the water between the top and bottom – an impossible task. Slowly, other scientists started paying attention to Joule; if work could be converted into heat, then heat could not be conserved, and perhaps heat could be converted back into work.

Joule’s revolutionary finding disturbed one particular scientist, the precocious William Thomson, later Lord Kelvin (1824–1907). Kelvin had joined Glasgow University at ten, was a professor by 22 and went on to a meteoric career in theoretical physics. He also had a strong practical streak, and made a fortune from his invention of telegraphy. Kelvin heard Joule describe his discoveries at a scientific meeting in Oxford in 1847 and afterwards he struggled with his inability to reconcile Joule’s finding that heat and work were incontrovertible with Carnot’s assumption that heat was indestructible but that the flow of heat drove work. The resolution of this conundrum produced two new laws for the Universe to ‘obey’: the First and Second Laws of Thermodynamics, joint products of the minds of Joule, Mayer, Kelvin, Helmholtz and Clausius. The First Law stated that heat and work (and other forms of energy) were incontrovertible but energy itself was indestructible. The infamous Second Law of Thermodynamics implied that although energy could not be destroyed in any conversion between its forms, it was inevitably ‘dissipated’ into other forms (mainly heat) less able to do work. Thus although work could be fully converted into heat, heat could not be completely converted into work, because, as Carnot had indicated, part of the heat had to be released to the cold sink in order that the flow of heat could continue and this heat could not then be converted to work. The implication of the Second Law was that all energy was continually running down or ‘dissipating’ into heat. Therefore the clockwork Universe must eventually run down unless there was something – or someone – outside the Universe to wind it back up again.

The First Law showed that heat could not be indestructible and this led to the resurrection of an old theory that heat (and perhaps all forms of energy) were hidden forms of motion. In hot water, water molecules move around very rapidly, while in cold water the molecules move slowly: when hot and cold water are mixed, the rapidly moving molecules of the hot collide with the slow-moving molecules of the cold, slowing the rapid molecules and speeding up the slow molecules which results in lukewarm water. Thus, the transfer of heat is really a transfer of motion. The exchange between all types of physical force in a common currency of energy gave a great unity to late-nineteenth-century science; a unity missing in the eighteenth century when electricity, magnetism, heat, light and work were all different and discussed in different terms. In the nineteenth century, because these apparently different physical forms could be interconverted they came to be regarded as different forms or manifestations of one thing: energy. But energy was not a type of matter but rather the motion or arrangement of matter. This concept of energy gave a new boost to the hopes of mechanists, who thought they might finally be able to describe everything in the Universe in terms of matter in motion. It has been argued that the origin of this energy concept was partly due to new concepts in accountancy accompanying the rise of industrialization: it is certainly true that energy acted as a new currency within physics keeping track of mechanical transactions. Prior to the 1850s ‘energy’ did not exist as a useful concept in science, afterwards it became the central concept. However, the word ‘energy’ entered the English language in the sixteenth century, meaning roughly ‘vigour of expression’, and later ‘vigour of activity’. Originally the word was derived from Aristotle’s term energeia, meaning actuality/activity; this in turn is derived from the Greek en for in or at and ergon for work. Today the word ‘energy’ has a rather schizoid existence, meaning something technical and quantifiable to scientists, but having a variety of metaphorical meanings in the wider community.

The scientific concept of energy did not arise purely from physics, but also at the same time from biology. Indeed the principle of energy conservation was simultaneously discovered by about twelve different scientists but was first formulated by the physicians Mayer and Helmholtz with reference to the forces of life. Robert Mayer (1814– 1878) was a German physician with an unlucky life. A mediocre student, he was arrested and expelled for joining a secret society. He eventually graduated and joined a ship bound for the East Indies as the ship’s doctor. At that time doctors still followed Hippocrates and Galen’s advice to bleed patients for a variety of maladies. While bleeding sailors in the East Indies, Mayer was alarmed to find that blood from the veins was much redder than usual, almost like arterial blood. At first, he worried he was puncturing arteries by mistake but local doctors assured him it was normal for venous blood to be redder in the tropics than in the cold north. This set Mayer thinking. He knew that Lavoisier had proposed respiration functioned to produce heat for the body and he also knew that the change from red to blue blood from arteries to veins was due to the removal of oxygen from the blood for respiration. Thus redder blood in the veins of a sailor in the tropics might be due to less respiration and heat production, which would make sense since the body needed to produce less heat in the tropics than the cold north. He also knew Lavoisier had shown men doing hard work respired more but had not given a convincing explanation of this important finding. Mayer proposed that fuel, heat and work were interconvertible: that it was possible to convert one into the others. Thus work done by men could be produced from heat (as in a steam engine) and this heat could in turn be produced by respiration (the burning of food). More work required more heat and more respiration as Lavoisier and Séguin had found experimentally. This reasoning, although partly wrong, was definitely getting closer to the secret of the energy of life.

When Mayer got back to Germany he wrote up his ideas in a scientific paper, but his thinking was muddled and the paper was rejected. On a second attempt he sent the paper to von Liebig, who published it in 1842. However, when von Liebig published soon after a related theory, Mayer accused him of plagiarism. As Schwann would have agreed, it was not wise to oppose the powerful von Liebig. Mayer then got into even deeper water when he started a priority dispute with Joule as to who had first thought of the conservation of energy. But Mayer lost both arguments due to his unestablished position. The ‘Joule’ is now the standard scientific unit of energy and the ‘Kelvin’ the standard unit of temperature, while Mayer’s name is nowhere to be seen in the virtual world of scientific units. Understandably, he became depressed, suffering a mental breakdown and attempting suicide.

Mayer’s ideas on the conservation of forces were not sufficiently general and quantitative to convince most scientists that something important had been discovered. This situation was dramatically changed by the great German physiologist Hermann von Helmholtz (1821–94), who in 1847 at twenty-six published his famous paper on the conservation of force. Helmholtz gave an exact quantitative definition of energy, explaining how the conservation of energy followed naturally from the known laws of physics. Using these principles, he suggested that heat and work generated by animals must derive entirely from the burning of food in respiration. Although Helmholtz was strongly sympathetic to von Liebig’s work, he pointed out that the vital force was incompatible with the conservation of energy (because the vital force could be converted into physical forces but not vice versa), and must thus be discarded by the new science of energy. Helmholtz was a founding member of a school of German physiologists (known variously as the Helmholtz, Berlin or 1847 School of Physiologists) who sought to explain all biological processes in terms of known physical, rather than vital, forces.

According to Helmholtz’s version of the conservation of energy, there was a single, indestructible and infinitely transformable energy basic to all nature. This ‘Energy’ was more fundamental to the Universe than matter and force, as the overarching theory of the conservation of energy constrained the manifest forms of matter and motion. Energy was well on its way to replacing God. The good news of the First Law was that the Universe was now a vast reservoir of protean energy awaiting conversion into work. The bad news of the Second Law was that this conversion was taxed by the dissipation of some energy into heat. Although all forms of energy were equal, some forms were more equal than others.

The discovery of the conservation of energy was partly due to the recognition that any quest to build a perpetual-motion machine was doomed. In the eighteenth century the French Academy of Sciences had set up a commission to examine proposals for building such a mythical machine: although many tried (including the young Mayer) all had failed. Such a machine would produce motion and work out of nothing. It would be an ‘unmoved mover’, something that Aristotle had associated with God alone. The recognition that perpetual motion was impossible led to the idea that all motion must arise from some prior, actual or potential motion: no change without a prior change. Therefore the whole history of the Universe was locked into one single causal web. Helmholtz criticized von Liebig’s concept of the vital force powering muscle contraction because the concept allowed the possibility of a perpetual motion machine which he considered impossible. But if energy conservation prevented the vital force from acting, some thought it would also prevent God interfering with the material world. Lord Kelvin magnanimously gave God a special dispensation to create or destroy energy. But others were less generous, relegating Him to the role of creating a fixed amount of energy at the start of the Universe and then sitting impotently on the sidelines as the consequences of His creation unfolded. Surprisingly some physicists now believe that the net amount of energy at the beginning of the Universe was zero, so perhaps it was God who was lacking in generosity.

The ancient Greeks said Prometheus had stolen fire from the gods, given it to mankind and with it part of their divine knowledge and power. Now, through Helmholtz and the others, mankind had acquired the concept of energy itself, and with it a greatly increased power for good or evil. If this concept of energy could be used to understand the secret of life and death, then perhaps death itself could be conquered and humans might at last become immortal gods.

The relation between respiratory heat production and muscle work and in general the coupling between respiration and energy use in the body still remained obscure throughout the nineteenth century. It was gradually established that respiration – oxygen consumption, carbon dioxide and heat production – occurred within the tissue cells, rather than in the lungs or blood. It was thus suggested that muscles might work as biological steam engines using the heat generated by respiration to drive contraction. But by the end of the century, it was realized that this would not work, as the Second Law of Thermodynamics indicates that heat is a very inefficient source of work unless the temperature difference between machine and environment is very high. At normal physiological temperatures a heat engine would therefore be extremely inefficient, generating very little work for the amount of food burnt. The only realistic way of using respiration to drive muscle contraction was to bypass heat production and pass the energy released by respiration through some intermediate energy store to muscle contraction, without releasing the energy as heat. But it took another century to work out how this feat was achieved.

The historical trail we have followed in pursuit of the secrets of life and energy has branched many times as the questions have multiplied, and the answers have led us off into territory ever more obscure and abstruse. To summarize, before pressing on in the next chapters to the summit of present understanding of body energy: we started by looking at the general modes of biological explanation in early cultures where energy and life were not distinguished from each other and where all movement and change were attributed to anthropomorphic souls, gods or spirits. Energy, enthusiasm and life were given by the gods and equally spirit and health could be taken away by the gods or devils. Mechanisms were not considered, because ‘mechanism’ was not involved. In ancient Greece and Rome the role of gods and souls gradually diminished. Energy came in the form of pneuma, a spirit of the air, circulating in the body and providing the ‘go’ of life. In Renaissance and Enlightenment Europe, spurred on by advances in technology, gods and souls were ejected from science and replaced by cold mechanics. Crucially, hypotheses were now tested by experiment rather than rational plausibility and this was aided by the injection of mathematics into scientific theories and experiments. Pneuma and spirits were replaced by ‘forces’ and ‘laws’. A component of the air, oxygen, was found to be essential to life and consumed inside the living body in the process of burning digested food, resulting in the production of body heat. This process of respiration was eventually found to be located in the cells of the body and carried out by enzymes, the molecular machines of the cell. The various forces of nature were found convertible between each other and into movement and heat and, thus, were united in the common concept of energy, the universal source of all movement and change. The body then became an energy converter (or engine), channelling the energy released by burning food into movement and thought, but how exactly this was effected was unknown.

The appealing idea of the history of science as a continuous ascent towards the pinnacle of modern truth, is, of course, anathema to most historians. They point out this view of history arises from taking the contemporary truth and weaving a narrative towards it – carefully selecting from the past. My brief historical overview gives little idea of how scientists really thought and operated in the past. It does, however, give us a sense of where our present-day concept of energy came from and how it evolved; and now we must follow it right up to the constantly moving present, where a number of shocks await.

Chapter 3 ENERGY ITSELF
WHAT IS ENERGY?

I taught bioenergetics (the science of body energy) in Cambridge for many years before I realized that I did not, myself, understand what energy was. Tutorials are meant to be cosy but fiercely intellectual chats between a teacher and one or two students. However, teachers can often rattle on without knowing what they are talking about. One fine day I discovered that was true of me and energy. Part of the problem with energy is that it is an abstract idea, so that one answer to the question ‘What is energy?’ is ‘A concept existing in a scientist’s head’. But another, more subtle problem is how the concept of energy has evolved historically, so that many layers of meaning, not always consistent, have been superimposed on the words and symbols. So take heart, if at first you do not understand the meaning of energy, it will not necessarily disqualify you from either doing scientific research or teaching bioenergetics at Cambridge! In science, as in life, you do not necessarily have to understand a concept in order to be able to use it.

According to current scientific ideas, energy is not an invisible force field coursing through the body, moving arms and legs and cooking up thoughts in the brain like some benign ghost dashing around pulling the levers of body and mind. The modern idea of energy is more like that of money. Money gives the capacity to buy things, coming in many forms, such as coins, notes, cheques, credit cards, bank accounts, bonds, gold etc. It can be used to buy many sorts of things, such as hats, houses and horses. Money allows the exchange of these things at a fixed rate, so that I can, for example, exchange a fixed quantity of coins for one horse. ‘Energy’ is a capacity for movement or change in a physical or biological system. It comes in many forms, such as chemical energy, electrical energy, or mechanical energy and can be used to ‘purchase’ many forms of change, such as movement, chemical change, or heating. Energy quantifies the exchange between these things at a fixed rate, so that, for example, a certain amount of heating requires the expenditure of a certain amount of chemical energy. One important difference between money and energy is, however, that money and monetary value are not exactly conserved. You may pay £100,000 for a house one year, selling it for £110,000 or £90,000 the next year without having altered or improved the house and this £10,000 does not suddenly appear or disappear from elsewhere in the economy. You can burn a £10 note and money simply disappears in smoke. Neither money nor monetary value is absolutely conserved: there is no Economic equivalent to the First Law in Thermodynamics. If there was, Economics would be easier but we might also be poorer. Energy is strictly conserved, as expressed by the First Law of Thermodynamics, which states that during any change of any sort the total amount of energy in the Universe stays the same. If you use one hundred units of energy to raise a rock one hundred feet in the air, on your return a year later lowering the rock to the ground one hundred units of energy will be released. It may not be released in wholly desirable ways – the energy may be released as heat, sound or work depending on how the rock is lowered, but when the energy released is added up the total will be one hundred units.

Money or monetary value is an abstract concept since it can reside in very different objects, such as coins or a bank account. Energy is similarly abstract since it is contained in many different types of thing, while not actually being them; energy rather is their capacity to produce movement or change. Energy is not in addition to the things themselves: it is rather as if an accountant were examining the situation, assessing the capacity for movement or change. For example if a rock is balanced at the edge of a chasm, it is possible to work out that if it were tipped into the chasm so much energy would be released as movement, noise, heat etc. Before the rock is moved, this energy does not reside in the rock or chasm any more than monetary value resides in coins or horses: this is because energy or monetary value are not tenuous forms of matter, but rather ways of quantifying the potential for change. Energy quantifies the capacity for movement or physical change within any particular situation.

Energy is like money in another way. Money does not determine how or when it is to be spent; that is determined by the people spending it. Similarly, a rock balanced over a chasm may have a lot of energy but this does not determine if or when the rock may fall. Rather it determines whether the rock can fall or not. The presence of a million dollars does not determine how or when it will be spent but does mean that x number of houses, y amount of strawberries or z number of horses could be bought. Similarly the presence of one million units of energy does not determine how or when the energy will be used, but it does mean that x amount of heat, y amount of movement or z amount of electricity could be produced.

The great American physicist Richard Feynman warned us of the abstract nature of energy in his famous Lectures on Physics:

‘It is important to realize that in physics today, we have no knowledge of what energy is. We do not have a picture that energy comes in little blobs of a definite amount. It is not that way. However, there are formulas for calculating some numerical quantity … It is an abstract thing in that it does not tell us mechanisms or reasons for the various formulas.’

So energy is not a thing or a substance. We can calculate it, using the figures for predictions, but have no idea what it is in itself. Energy seems just an abstract accounting concept like money quantifying the amount of movement that could be produced by a particular system. How boring! Yet, according to physics, energy is perhaps the most fundamental property of the Universe. Energy is the one constant conserved through all change. Everything can be created from or dissolved into energy, including even matter itself: which is demonstrated by atomic explosions and Einstein’s famous equation E = mc². In this rather abstract scheme of things, energy is the ultimate substance and fabric of the world, from which all else evolves and into which all else ultimately dissolves.

But energy itself does not produce movement or change. So what does? Newton said all movement or change is brought about by forces. In our lives we experience only two types: gravitation and contact forces. Gravitational force pulls everything towards the earth’s centre and causes all heavenly (and not so heavenly) bodies to attract each other. Contact forces occur when we push or pull something; when I lift a chair; when a car hits a lamppost; or when a volcano explodes. Gravitational force exists because every bit of matter is attracted to every other bit, causing them to accelerate towards each other. All the contact forces are different manifestations of one immensely powerful force: the electric force. Electric force is the force of attraction or repulsion between all charged matter. Gravitational force and electric force account for virtually all movement and change in our universe. There are two other forces known: strong nuclear force and weak nuclear force but their range of action is so small, they can only be observed by breaking open the nucleus of an atom. Thus nuclear forces have no apparent effect either on biology or our everyday lives.

Although gravitational force is important for large objects like us, it has no significance for small objects like cells. The electric force is – roughly – one thousand million million million million million million times stronger than the gravitational force and is the only force that matters at the level of molecules and cells. Gravitational force causes attraction – that is, two objects will accelerate towards each other. But the electric force causes either repulsion or attraction depending on whether the matter carries the same or different charges: opposites attract, likes repel. The electron carries a negative charge: the proton a positive charge. Everything, including our bodies, can be considered made up of different arrangements of protons and electrons. (There are also neutrons, but they have no charge, and behave like an electron and a proton stuck tightly together.) Everyday objects are made up of approximately equal numbers of electrons and protons. If this were not so, an excess of positive or negative charge would create a huge force pushing out (or exploding) the extra charge, leaving a roughly neutral group of electrons and protons. The power of the electric force is truly immense. If two people, standing at arm’s length, each had one per cent more electrons than protons in their bodies, they would be blown apart by an electric force sufficient to move the weight of the entire earth.

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