74 SELECTIONS FROM HUXLEY 



but well-authenticated facts, and the immediate conclusions 

 which they force upon the mind. 



But the mind is so constituted that it does not willingly 

 rest in facts and immediate causes, but seeks always after a 

 5 knowledge of the remoter links in the chain of causation. 



Taking the many changes of any given spot of the earth's 

 surface, from sea to land and from land to sea, as an estab- 

 lished fact, we cannot refrain from asking ourselves how these 

 changes have occurred. And when we have explained them, 

 10 as they must be explained by the alternate slow movements 

 of elevation and depression which have affected the crust of 

 the earth, we go still further back, and ask, Why these move- 

 ments ? 



I am not certain that any one can give you a satisfactory 

 15 answer to that question. Assuredly I cannot. All that can 

 be said, for certain, is, that such movements are part of the 

 ordinary course of nature, inasmuch as they are going on at 

 the present time. Direct proof may be given, that some parts 

 of the land of the northern hemisphere are at this moment 

 20 insensibly rising and others insensibly sinking ; and there is 

 indirect, but perfectly satisfactory, proof, that an enormous 

 area now covered by the Pacific has been deepened thousands 

 of feet, since the present inhabitants of that sea came into 

 existence. 



25 Thus there is not a shadow of a reason for believing that the 

 physical changes of the globe, in past times, have been effected 

 by other than natural causes. 



Is there any more reason for believing that the concomitant 

 modifications in the forms of the living inhabitants of the globe 

 30 have been brought about in other ways ? 



Before attempting to answer this question, let us try to 

 form a distinct mental picture of what has happened, in some 

 special case. 

 The crocodiles are animals which, as a group, have a very 



