SCIENCE IN THE ANCIENT WORLD 45 



shape, but identical in substance. Empedocles ex- 

 plained differences in properties by different combina- 

 tions of his four elements. Democritus went further, 

 and referred differences in properties to differences 

 in size, shape, position and movement of particles 

 of the same ultimate nature. His theory, as trans- 

 mitted to us by Lucretius, effects a wonderful simpli- 

 fication in the mental picture of nature previously 

 held. In fact, the picture is too simple. The 

 atomists passed unconsciously over difficulties still 

 unsolved after the lapse of twenty-four centuries. 

 Fearlessly they applied their theory to problems of 

 life and consciousness which still defy explanation 

 in mechanical terms. Confidently they believed 

 they had left no mysteries, all blind to the great 

 question whether the conception of atoms they had 

 framed to describe phenomena corresponded with an 

 ultimate reality any more nearly than did the simple 

 sense-perceptions it was invoked to explain. 



Nevertheless, the Democritan atomic theory is 

 nearer to the views now held by physicists than any of 



the systems which preceded or replaced 

 Aristotle. ., \ ., . , , . , ,, 



it, and its virtual suppression under the 



destructive criticism of Aristotle (c. 384-322) must 

 be counted a loss to mankind. 



The success of the Aristotelian philosophy shows 

 the danger to physical theories, even though sound 

 in themselves, when they are not founded on a broad 

 and detailed basis of experimental fact. Because 

 the consequences of the atomic theory did not agree 

 with Aristotle's preconceived ideas, he rejected it 

 altogether, and, in the absence of definite confirmatory 



