214 The Science of Life. 



idea. Empedocles (495-435), whom Osborn calls "the 

 father of the evolution idea", pictured the gradual 

 origin of diverse forms first plants and then animals 

 through the chance play of the combining force of 

 love and the separating force of hate upon the four 

 elements fire, water, earth, and air. The first forms, 

 being monstrous failures, were eliminated and replaced 

 by more successful though still fortuitous products of 

 Nature's spontaneity. Here we find a glimmering of 

 the idea of the survival of the fittest or natural 

 selection. Democritus (450 B.C.?), famous as an early 

 materialist and perhaps the first comparative ana- 

 tomist, recognized the general occurrence of fitness, 

 even of single structures and organs, but he does not 

 seem to have had any theory of its origin. He advanced 

 some views in regard to heredity, which are usually 

 spoken of as suggestive of pangenesis. Anaxagoras 

 (500-428), on the other hand, was the founder of teleo- 

 logy, in so far as he began to invoke the aid of intelligent 

 design to separate out and arrange the germs of life 

 which existed from all time in the air or ether. 



Even when the pre-Aristotelian philosophers conde- 

 scended to statements with some direct relation to 

 facts, it is difficult for us at this distance of time to 

 understand how much they really meant. But there is 

 little of this difficulty in regard to Aristotle, who com- 

 bined in equal excellence the qualities of philosopher and 

 naturalist, and, far ahead of his age, made the transition 

 from guess-work to induction. He held the idea of a 

 gradual progression in nature from the inorganic to the 

 organic, and from one grade of life to another. As to 

 the factors in this progression, he does not seem to have 

 worked out the problem concretely; he refused the 

 suggestion that adaptive structures could be the result 

 of the elimination of the unfit, and believed that ' ' nature 

 produces those things which, being continually moved 

 by a certain principle contained in themselves, arrive at 

 a certain end ". He expounded the doctrine of a " per- 

 fecting principle" or "physical formal cause" which 

 struggled with the " physical material cause" or matter 

 itself, and worked out a continuous and progressive 



