12 Permanence and Evolution. 



DARWIN AND LYELL: COMPARISON 

 AND CONTRAST. 



THERE is a great difference in kind between 

 Lyell's hypothesis (if hypothesis it can be called) 

 of the unity of past and existing geological 

 causes and the hypothesis of evolution. The 

 former has to do almost entirely with mechanical 

 motion, and the causes producing change are, 

 in the case of aqueous agents, exactly in the 

 case of igneous, approximately known. In the 

 other case, both effects and causes are infinitely 

 complicated and ill-understood. There is a 

 great fallacy in putting things quantitatively, 

 which are in truth matters of kind. It is said 

 that species differ far more than varieties and 

 varieties than family strains, and that this 

 greater difference is the result of lapse of time ; 



