THE DOCTRINE OF EVOLUTION. 581 



close combination. But since the cooling of the earth to a point at 

 which its solid crust acquired stability, since the ancestors of the 

 amphioxus began to swim in the seas and worms to crawl in the 

 ground, if you could at almost any time have visited the earth, 

 you would doubtless have found things going on at measured pace 

 very much as at present here and there earthquake and ava- 

 lanche, fire and flood, but generally rain falling, sunshine quicken- 

 ing, herbage sprouting, creatures browsing, all as quiet and peace- 

 ful as a daisied field in June, without the slightest presage of the 

 continuous series of secular changes that were gradually to trans- 

 form the Carboniferous world into what was by and by to be a 

 Jurassic world, and that again into what was after a while to be 

 an Eocene world, and so on until the aspect of the world which we 

 know should quietly emerge. 



The influence of the new geology upon men's habits of thought 

 and upon the drift of philosophic speculation was profound. It 

 was proved beyond question that the world was not created in the 

 form in which we find it to-day, but has gone through many 

 phases of which the later are very different in aspect from the ear- 

 lier ; and it was shown that, at any rate so far as the inorganic 

 world is concerned, its changes can be much more satisfactorily 

 explained by a reference to the ceaseless, all-pervading activity of 

 gentle, unobtrusive causes such as we know, than by an appeal to 

 imaginary catastrophes such as we have no means of verifying. 

 It began to appear, also, that the facts which form the subject- 

 matter of different departments of science are not detached and 

 independent groups of facts, but that all are intimately related one 

 with another, and that all may be brought under contribution in 

 illustrating the history of cosmical events. Thus, in one way and 

 another, about the time when Mr. Darwin set out on his memo- 

 rable voyage around the world, men were beginning to arrive at 

 a vague general conception of evolution as an orderly succession 

 of phases of nature, in which any given phase is produced from 

 an antecedent phase through the agency of causes which are like 

 those now in operation, and which must therefore admit of defi- 

 nite scientific study and explanation. 



The time had at length arrived when the facts of organic life 

 could be brought under this general conception. As long as it 

 was supposed that each geologic period was separated from the 

 periods immediately before and after it by Titanic convulsions 

 which revolutionized the face of the globe, it was possible for 

 men to acquiesce in the supposition that these convulsions wrought 

 an abrupt and wholesale destruction of organic life, and that the 

 lost forms were replaced by an equally abrupt and wholesale su- 

 pernatural creation of new forms at the beginning of each new 

 period. But as people ceased to believe in the convulsions, such 



