GENERAL SUMMARY. 333 



ory is not, as was at first thought, an alarming blow 

 at theism. It is simply one step more in a direc- 

 tion in which thought has long been tending. 

 In the early ages of thought every phenome- 

 non of nature was looked upon as the direct re- 

 sult of supernatural agencies. A god was assumed 

 to account for every unexplained fact of nature. 

 But gradually this crude conception has been re- 

 placed by the idea of a single God governing nature 

 by law. Now the theory of evolution is sim- 

 ply a part of this general tendency, assuming that 

 law has also produced the present organic world. 

 It has met naturally with a momentary opposition, 

 as did the Copernican theory, or the theories of 

 geology. But, like the other theories, it has been 

 found to demand rather than do away with the 

 necessity of a Creator. It is, then, a purely scientific 

 theory concerning the laws of the organic world. 



As a scientific theory it is now generally regarded. 

 Scientists claim that though the theory has not been 

 proved, and probably never will be, it has been ren- 

 dered so probable that it is almost beyond the 

 reach of question. Every possible source of evi- 

 dence which has promised results has been studied. 

 The effects of domestication and the changes of 

 conditions in wild animals have been noted. The 

 results here have proved that species are not rigidly 

 fixed, but are subject to a very great amount of 

 variation.. It has been proved that the differences 

 between the varieties thus arising may be greater 

 than that between species, except in the single 

 character of sterility ; and for this exception an ex- 



