402 Darivin, and after Darzvin. 



as they occur in organic nature. With the adapta- 

 tions — if they can properly be so called — which occur 

 in all the rest of nature, and which go to constitute the 

 Cosmos as a whole so wondrous a spectacle of 

 universal law and perfect order, this doctrine is but 

 indirectly concerned. Nevertheless, it is of course 

 fundamentally concerned with them to the extent that 

 it seeks to bring the phenomena of organic nature into 

 line with those of inorganic ; and therefore to show 

 that whatever view we may severally take as to the 

 kind of causation which is energizing in the latter we 

 must now extend to the former. This is usually 

 expressed by saying that the theory of evolution by 

 natural selection is a mechanical theory. It endea- 

 vours to comprise all the facts of adaptation in organic 

 nature under the same category of explanation as 

 those which occur in inorganic nature — that is to 

 say, under the category of physical, or ascertainable, 

 causation. Indeed, unless the theory has succeeded 

 in doing this, it has not succeeded in doing anything — 

 beyond making a great noise in the world. If Mr. 

 Darwin has not discovered a new mechanical cause in 

 the selection principle, his labour has been worse than 

 in vain. 



Now, without unduly repeating what has already 

 been said in Chapter VIII, I may remark that, what- 

 ever we may each think of the measure of success 

 which has thus far attended the theory of natural 

 selection in explaining the facts of adaptation, we ought 

 all to agree that, considered as a matter of general 

 reasoning, the theory does certainly refer to a vera 

 causa of a strictly physical kind ; and, therefore, that 

 no exception can be taken to the theory in this respect 



