Guy Brown - The Energy of Life:

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.