Passage III

HUMANITIES: This passage is adapted from Thomas H. Greer's A Brief History of the Western World (©1982 by Harcourt Brace Jovanovich, Inc.).

The earliest Greek philosophers (sixth century B.C) began by criticizing the prevailing nature-myths. They found it hard to believe that earthquakes were caused by the stamping of Poseidon or that lightning was a bolt from Zeus. They made the crucial intellectual leap from a primitive, anthropomorphic [attributing human characteristics to nonhuman things] view of nature to a rational, analytic view.

One of the basic questions they sought to answer through rational analysis relates to the composition of the physical universe: What are the elements from which all material things are made? Around 600 B.C., Thales of Miletus (in Asia Minor) hypothesized that water is the basic ingredient. This was a logical inference, since water seems to be present, in various forms, throughout the world of space and matter. It fills the sea, rivers, and springs; it falls from the sky; it is found in the flesh and organs of animal bodies. And, under varying conditions of temperature and pressure, it changes from a liquid to a solid or a vapor. Thales was no doubt aware that his hypothesis did not explain all the varied appearances of matter; but he and other Greek thinkers were convinced that nature, in its unseen essence, is far simpler than it appears to be.

Though later philosophers rejected Thales belief that everything can be reduced to water, they agreed that he was on the right track. Some believed the prime substance to be air or fire; others concluded that there are four basic elements: earth, air, fire, and water. But during the fifth century B.C. Democritus of Abdera (in Thrace) developed the hypothesis that all physical things are formed by combinations of tiny particles, so small that they are both invisible and indivisible. He called them atoms. Democritus‘ atoms are identical in substance but differ in shape, thus making possible the great variety of perceived objects in the world. They are infinite in number, everlasting, and in constant motion. They account, said Democritus, for everything that has been or ever will be. Democritus offered no empirical evidence to prove the existence of atoms, but the fact that he could conceive this remarkable hypothesis demonstrates the far-reaching achievement of Greek rational thought.

Rational thought was also applied to diseases. In he fifth century B.C., Hippocrates of Cos (an island in the Aegean)openly challenged traditional supernatural explanations of illness. He insisted that natural causes be looked for and that natural means be used to treat disease. He was one of the first physicians to stress the influence of environment (climate, air, and water) on health. His most notorious theory, however, was that of "humors." The human body, Hippocrates believed, contains four humors (fluids): blood, phlegm, yellow bile, and black bile, When these are in proper balance, the individual enjoys normal health. But when the balance becomes disturbed, the physician must use his skill to restore it. This unproved theory was widely accepted in the West until the eighteenth century—and sometimes brought suffering or death (from bloodletting).

Turning to more abstract and universal matters, the philosopher Parmenides of Elea (in southern Italy) tackled the perplexing issue of permanence versus change in the world. He convinced himself that everything in the universe must be eternal and unchangeable. Change requires motion, he reasoned, and motion requires empty space. But empty space equals nonexistence, which by definition does not exist. Therefore, he concluded, motion and change are impossible. Parmenides readily admitted that some things appear to move and change; but this must be an illusion of the senses, he said, because it is contradicted by logic. And logic, the Greek philosophers thought, is the most reliable test of truth.

Logic did not always lead to the same answers, however. While Parmenides satisfied himself that matter was unchanging and permanent, another Greek reached the opposite conclusion. Heraclitus of Ephesus (in Asia Minor) insisted that the universe, instead of standing still, is in continuous motion. He declared that a person cannot step into the same river twice—in fact, the river is changing even, as one steps into it. This doctrine proved most disturbing, for if everything is constantly changing (including ourselves), how can we gain true knowledge of anything? By the time our mind has been informed, the object of our attention is no longer what it was！