Evolution of Evolution-Theory. 213 



But simple as the idea is, it has been slowly evolved, 

 gaining- content as research furnished fuller illustration, 

 and gaining clearness as criticism forced it to keep in 

 touch with facts. It has slowly developed from the 

 stage of suggestion to the stage of verification; from 

 being an a priori anticipation it has become an inter- 

 pretation of nature ; and from being a modal interpreta- 

 tion it has advanced to the rank of a causal theory. 



Almost all naturalists now accept the Doctrine of 

 Descent, here wisdom is certainly justified of her chil- 

 dren ; but it is quite another thing to be ready with a 

 Theory of Evolution. In short, the fact of organic evo- 

 lution forces itself upon us, but a study of the factors is 

 still a lesson in uncertainties. 



In estimating the guesses at truth which abound in 

 the writings of the early Greek philosophers, we must 

 avoid two opposite errors, on the one hand, Greek 

 that of reading into them a scientific value Period, 

 which they are far from possessing; on the other hand, 

 that of unduly depreciating them because they were 

 imaginative, not inductive. 



Thales (624-548 B.C.), the Ionian, was one of the first 

 to suggest the theory that all things arose from water, 

 a theory, as Professor Osborn remarks, natural "in a 

 country surrounded by warm marine currents prodigal 

 with shore and deep-sea life"; Anaximander (611-547), 

 the Milesian, had some crude notion of metamorphoses, 

 and forestalled the grotesqueness of some modern ver- 

 sions of Recapitulation in his picture of the emergence 

 of ancestral man from an encapsuled fish-like stage 

 wafted ashore like a mermaid's purse; Anaximenes 

 (588-524) had a theory of a primordially prolific earth- 

 slime, which seems like a far-off suggestion of one of 

 Oken's dreams. 



We reach firmer ground when we pass from the 

 earliest schools to those who are often called the Phy- 

 sicists. Heraclitus (535-475) held a vividly kinetic 

 conception of the universe, as a system of continuous 

 movements, a view as familiar to the Greek mind as it 

 is in modern physics, and perhaps furnishing one of the 

 elements which went to the composition of the evolution 



