"THE ORIGIN OF SPECIES." 319 



phenomena of biology, a firm base of operations whence 

 it may conduct its conquest of the whole realm of 

 nature. 



History warns us, however, that it is the customary 

 fate of new truths to begin as heresies and to end as 

 superstitions ; and, as matters now stand, it is hardly 

 rash to anticipate that, in another twenty years, the 

 new generation, educated under the influences of the 

 present day, will be in danger of accepting the main 

 doctrines of the " Origin of Species," with as little re- 

 flection, and it may be with as little justification, as 

 so many of our contemporaries, twenty years ago, re- 

 jected them. 



Against any such a consummation let us all devoutly 

 pray ; for the scientific spirit is of more value than its 

 products, and irrationally held truths may be more 

 harmful than reasoned errors. Now the essence of the 

 scientific spirit is criticism. It tells us that whenever 

 a doctrine claims our assent we should reply, Take it 

 if you can compel it. The struggle for existence holds 

 as much in the intellectual as in the physical world. 

 A theory is a species of thinking, and its right to exist 

 is coextensive with its power of resisting extinction 

 by its rivals. 



From this point of view, it appears to me that it 

 would be but a poor way of celebrating the Coming 

 of Age of the " Origin of Species," were I merely to 

 dwell upon the facts, undoubted and remarkable as 

 they are, of its far-reaching influence and of the great 



