II THE ORIGIN OF SPECIES 73 



4 'The mode of investigation," says Mr. Mill, " which, from 

 the proved inapplicability of direct methods of observation and 

 experiment, remains to us as the main source of the knowledge 

 we possess, or can acquire, respecting the conditions and laws of 

 recurrence of the more complex phenomena, is called, in its 

 most general expression, the deductive method, and consists of 

 three operations : the first, one of direct induction ; the second, 

 of ratiocination ; and the third, of verification." 



Now, the conditions which have determined the 

 existence of species are not only exceedingly com- 

 plex, but, so far as the great majority of them are 

 concerned, are necessarily beyond our cognisance. 

 But what Mr. Darwin has attempted to do is in 

 exact accordance with the rule laid down by Mr. 

 Mill ; he has endeavoured to determine certain 

 great facts inductively, by observation and experi- 

 ment ; he has then reasoned from the data thus 

 furnished ; and lastly, he has tested the validity of 

 his ratiocination by comparing his deductions with 

 the observed facts of Nature. Inductively, Mr. 

 Darwin endeavours to prove that species arise in 

 a given way. Deductively, he desires to show 

 that, if they arise in that way, the facts of distri- 

 bution, development, classification, &c., may be 

 accounted for, i.e. may be deduced from their mode 

 of origin, combined with admitted changes in 

 physical geography and climate, during an inde- 

 finite period. And this explanation, or coinci- 

 dence of observed with deduced facts, is, so far as 

 it extends, a verification of the Darwinian view. 



There is no fault to be found with Mr. Darwin's 



