PRINCIPLE OF NATURAL SELECTION, 21 / 



as its effects. To have discovered the cause 

 by an analysis of the effects would indeed have 

 been a triumphant inductive discovery. 



He selected wisely the material on which 

 to concentrate the investigation ; he said : " I 

 soon perceived that selection was the keystone 

 of man's success in making useful races of 

 animals and plants. But how selection could 

 be applied to organisms living in a state of 

 nature remained for some time a mystery to 

 me." In his study of domestic races he ob- 

 served both the effects (races) and the cause 

 (selection), and did not, except perhaps in 

 details, reason deductively from the cause to 

 discover the effect, or inductively from the 

 effects to discover the cause. The effort to 

 extend the principle of selection by induction 

 to animals and plants in a state of nature failed 

 because it was impossible to see how the prin- 

 ciple could be applied. The inductive problem 

 was apparently as far from solution as at the be- 

 ginning; he was still groping in the dark. It 

 would be a bootless speculation to try to answer 

 the question whether Darwin could ever have 

 solved by a study of adaptations the problem 

 which he set for himself. It would be hardy 

 to hold that a man with Darwin's intellectual 

 and moral resources, with his clear conception 



