The Energy of Life:
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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.