Atomism in Ancient Medical History.

THE history of the development of the atomic theory is usually imagined to be the exclusive province of chemistry and physics, and there is a tendency to suppose that molecular biology is one of the most recent products of twentiethcentury science. For these reasons it is surprising to discover that the paths of the corpuscular world-view and theoretical physiology crossed more than two thousand years ago and that this encounter resulted, not in a casual and passing acquaintance, but in an important and productive liaison which continued, albeit with interruptions, over a period of twenty centuries. Far from being cloistered academicians the pre-Socratic philosophers of ancient Greece were expected to be the brains of their community, intellectuals in the most responsible sense of that term. They were consulted by their fellow townspeople concerning every type of problem, practical as well as speculative, and ranging from epistemology to sanitary engineering. Indeed, their formal philosophizing may have been a pleasant diversion of their spare moments. Clearly they were not specialists. All human knowledge was their 'field', biology as well as astronomy, physics, chemistry and metaphysics, not to mention psychology, sociology and ethics. In addition to theorizing about the life processes, some of them undoubtedly prepared and dispensed medical treatments. Empedocles, we know, claimed miraculous 'cures'. In view of his personality the treatment, in this instance, probably consisted of a mixture of hocus-pocus and genuine therapy. The physiological opinions ofthe philosophers, together with the ancient practices of the priests of Asclepius and the usages of the gymnasia superintendents, formed the basis of Greek medicine.' Biological observations sometimes exerted a profound influence on the cosmological speculations ofthe pre-Socratics. For example, Thales' choice ofwater as the primal element may very well have been the product of a number of biological observations-that water is vital to the life processes, that blood and the other body fluids are composed mostly of water, that the generative seed of all creatures is moist, that the sea teems with life, that water condenses from the breath. We find in ancient Greek philosophy two well-defined examples of what we might properly call proto-atomism prior to the true atomism of Leucippus and Democritus. The first of these is the geometrical atomism of the Pythagoreans which found its most influential presentation in the Timaeus of Plato.2 Later in our discussion we will return to Plato's application of this type of corpuscular theory to physiological phenomena. The second is the famous 'seed' hypothesis