THE DEVELOPMENT OF THE SCIENTIFIC METHOD 71 



oras of Samos gave the philosophy of science a mystical turn 

 that took it far from the path to which it had been directed 

 by Thales and Hippocrates. Then the whole trend of Greek 

 thought was revolutionized by the teaching of Socrates. In 

 his youth, Socrates studied physics, and it is interesting to 

 speculate as to what ^vould have happened if he had con- 

 tinued to be interested in science. But Socrates grew im- 

 patient with the difficulty he found in deducing science from 

 a single fundamental idea, and turned instead to the teaching 

 that it is the great business of life to practice the care of one's 

 own soul. Socrates followed Pythagoras in believing that 

 reality consists of abstract ideas and that mathematical truths 

 were divine and illustrated the nature of the mind of God, a 

 view that has been advocated to some extent by modern 

 mathematicians. Thus Socrates and Plato, his great follower, 

 rejected experimental science and established the priority of 

 mind over matter. 



The outstanding philosopher through whom the views of 

 the ancient Greeks were made available to a later world ^vas 

 Aristotle, who seems to have combined the po^ver of an orig- 

 inal and creative thinker with the instincts of a natural 

 teacher. Aristotle at the age of seventeen left Macedon for 

 Athens to study under Plato. He worked on mathematics 

 and physics and wrote treatises on astronomy and physics. 

 In these fields he followed the platonic philosophy and de- 

 duced the laws of nature from a priori assumptions, at the 

 same time adopting the conclusions of the Pythagoreans, who 

 used arithmetic relations as the basis of the physical world. 

 Thus he adopted the idea of Empedocles of Acragas in Sicily, 

 that matter is composed of four elements, each of which is 

 distinguished by two primary qualities: fire is hot and dry; 

 air, hot and fluid; water, cold and fluid; and earth, cold and 

 dry. After the death of Plato, Aristotle began more and 

 more to abandon these a priori assumptions and to rely on 

 observation. Perhaps because he was the son of a physician, 

 he turned to the field of biology, in which he made very rapid 

 progress. The material that Aristotle ^vrote on biology is in 



