FROM THALES TO LUCRETIUS. 17 



what is is no more real than what is not, and that 

 both are alike causes of the things that come into 

 being; for he laid down that the substance of the 

 atoms was compact and full, and he called them 

 what is, while they moved in the void which he called 

 what is not, but affirmed to be just as real as what is." 

 Thus did " he answer the question that Thales had 

 been the first to ask." 



Postponing further reference to this theory until 

 the great name of Lucretius, its Roman exponent, is 

 reached, we find a genuine scientific method making 

 its first start in the person of Aristotle. This remark- 

 able man, the founder of the experimental school, 

 and the Father of Natural History, was born 384 

 B. c. at Stagira in Macedonia. In his eighteenth 

 year he left his native place for Athens, where he 

 became a pupil of Plato. Disappointed, as it is 

 thought, at not succeeding his master in the Acad- 

 emy, he removed to Mytilene in the island of Lesbos, 

 where he received an invitation from Philip of Mace- 

 don to become tutor to his son, the famous Alex- 

 ander the Great. When Alexander went on his ex- 

 pedition to Asia, Aristotle returned to Athens, teach- 

 ing in the " school " which his genius raised to the 

 first rank. There he wrote the greater part of his 

 works, the completion of some of which was stopped 

 by his death at Chalcis in 322. The range of his 

 studies was boundless, but in this brief notice we 

 mustlimit our survey — and the more so becauseAris- 

 totle's speculations outside natural history abound ia 



