RETROSPECT 



After my prolonged restudy of the entire 

 twenty-four-century period of evolution thought 

 I am more than ever impressed with the evidence 

 of continuity in the development of the great 

 central idea of Evolution as first expressed in my 

 early course of lectures at Princeton in the year 

 1890. The main difference between the modern 

 idea of Evolution and the Greek idea is not due 

 to any essential difference between the Greek 

 mind and the modern mind, except in favor of 

 the former; it is due to the incalculable growth of 

 our knowledge, which, whether we will or not, 

 forces the principle of Evolution upon us as the 

 most comprehensive law of Nature that has been 

 discovered. 



When we compare Aristotle's Historia Ani- 

 malium of the fourth century b. c. with the stu- 

 pendous volumes of research of the present day, 

 which set forth in minutest detail the principles 

 of anatomy, physiology and biology — branches 

 to which Aristotle devoted merely a few lines or 

 sentences of exposition — we realize the wide con- 

 trast and wonder the more that the Greeks, with 

 their comparatively meagre and limited knowl- 

 edge, came so near the truth. 



349 



