314 THE COMING OF AGE OF [LECT. 



every living being on the globe was swept away, 

 to be replaced by a brand-new creation when the 

 world returned to quiescence. A scheme of nature 

 which appeared to be modelled on the likeness of a 

 succession of rubbers of whist, at the end of each of 

 which the players upset the table and called for a 

 new pack, did not seem to shock anybody. 



I may be wrong, but I doubt if, at the present 

 time, there is a single responsible representative of 

 these opinions left. The progress of scientific geo- 

 logy has elevated the fundamental principle of uni- 

 formitarianism, that the explanation of the past is to 

 be sought in the study of the present, into the position 

 of an axiom; and the wild speculations of the catastro- 

 phists, to which we all listened with respect a quarter 

 of a century ago, would hardly find a single patient 

 hearer at the present day. No physical geologist 

 now dreams of seeking, outside the range of known 

 natural causes, for the explanation of anything that 

 happened millions of years ago, any more than he 

 would be guilty of the like absurdity in regard to 

 current events. 



The effect of this change of opinion upon biological 

 speculation is obvious. For, if there have been no 

 periodical general physical catastrophes, what brought 

 about the assumed general extinctions and re-creations 

 of life which are the corresponding biological cata- 

 strophes? And, if no such interruptions of the 

 ordinary course of nature have taken place in the 

 organic, any more than in the inorganic, world, what 

 alternative is there to the admission of evolution ? 



