CONCLUSION. 231 



of its comparatively small value, and continued 

 the investigation until, by careful observation 

 of all collateral facts, he was able to combine 

 them into a body of positive evidence in sup- 

 port of a different or supplemental theory. 



Classification was with him an invaluable 

 instrument for extracting information from 

 bodies of facts. His works teem with compar- 

 ative tables and statements of results derived 

 from them. Analogical reasoning, with all its 

 strength and weakness, was utilized as a power- 

 ful instrument of suggestion. Induction was 

 constantly active in the formation of hypoth- 

 eses. He could leave nothing unexplained. 

 He made an hypothesis for everything, and 

 then tested it unmercifully by deduction. He 

 appreciated the immense importance of theory 

 to good observation, explained in the light of 

 his general theories great bodies of facts and 

 principles which had been discovered empiri- 

 cally, and anticipated many important conse- 

 quences of those theories. Whenever it was 

 possible he undertook to verify those anticipa- 

 tions ; but did not hesitate to make predictions 

 that he could not verify. And with all his 

 vast and accurate knowledge of facts and his 

 logical power, he frequently fell into erroneous 

 reasoning. 



