The Doctrine of Evolution. 439 



causes. The continual dropping that wears away stones 

 might have served as a text for the whole series of beautiful 

 researches of which he first summed up the results in 1830. 

 As astronomy was steadily advancing toward the proof that 

 in the remotest abysses of space the physical forces at work 

 are the same as terrestrial forces ; so now geology, in carry- 

 ing us back to enormously remote periods of time, began to 

 teach that the forces at work have all along been the same 

 forces that are at work now. In that early stage when the 

 earth's crust was in process of formation, when the tempera- 

 ture was excessively high, there were, of course, phenomena 

 such as can not now be witnessed here, but to find a parallel 

 to which we must look to certain other planets such as 

 violent atmospheric disturbances, and such as the dissociation 

 of chemical elements which we are accustomed to find in 

 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 avalanche, fire and flood, but 

 generally rain falling, sunshine quickening, herbage sprout- 

 ing, creatures browsing, all as quiet and peaceful as a daisied 

 field in June, without the slightest presage of the continuous 

 series of secular changes that were gradually to transform 

 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 latter are very 

 different in aspect from the earlier ; 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 ref- 

 ence to the ceaseless, all-pervading activity of gentle, unob- 

 trusive causes such as we know, than by an appeal to imagi- 

 nary catastrophes such as we have no means of verifying. 

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

 ject-matter of different departments of science are not de- 

 tached and independent groups of facts, but that all are 



