XII. 



UNVERIFIED DEDUCTIONS. 



EVERY apparently insignificant fact was 

 full of meaning to Darwin; and he made 

 it the occasion for what he used to call "fool's 

 experiments." His speculative powers em- 

 ployed themselves as actively and energetically 

 on the details of his investigations as on their 

 larger outlines; but he was as ruthless in test- 

 ing and rejecting his speculations as he was 

 facile in making them. When, however, he 

 had once established a principle, he followed 

 out the deductions from it with as much confi- 

 dence as if he had already secretly seen the 

 facts whose existence he suspected or thought 

 probable. It is important to note the caution 

 with which he usually stated his anticipations, 

 and to contrast with it the energy and confi- 

 dence with which he sought and worked out 

 the facts. He spent his life establishing the 

 consequences of his theories, but with all his 

 fidelity and persistence he had to leave many 

 things unproved; some for lack of time, others 



