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