263 FTKA-L CAUSES : THEIR BEAJUNO 



FINAL CAUSES : THEIE BEARING ON 

 GEOLOGIC HISTORY. 



CONCLUSION. 



" Natural History has a principle on which to reason," says 

 Cuvier, " which is peculiar to it, and which it employs advan- 

 tageously on many occasions : it is that of the conditions oj 

 existence, commonly termed j^/iaZ causes.'' 



In Geology, which is Natural History extended over all 

 ages, this principle has a still wider scope, — embracing not 

 merely the characteristics and conditions of the beings which 

 now exist, but of all, so far as we can learn regarding them, 

 which have ever existed, and involving the consideration of 

 not merely their peculiarities as races placed before us with- 

 out relation to time, but also of the history of their rise, in- 

 crease, decline, and extinction. In studying the biography, 

 if I may so express myself, of an individual animal, we have 

 to acquaint ourse] ves with the circumstances in which nature 

 has placed it, — its adaptation to these, both in structure and 

 instinct, — the points of resemblance which it presents to the 

 individuals of other races and families, — and the laws which 

 determine its terms of development, vigorous existence, and 

 decay. And all Natural History, when restricted to the pass- 



