394 PHILOSOPHICAL THOUGHT. 



tion between the exact and the biological (including the 

 mental) sciences was removed. But, fortunately for the 

 biological sciences, a second and equally important step 

 was taken about the same time, by which one of the 

 fundamental conceptions through which we fix our 

 comprehension of the phenomena of living matter re- 

 ceived likewise a clearer definition. The older terms of 

 development and progress, denoting not merely change 

 but change from the lower, simpler, and less interesting 

 and valuable, to the higher, more complex, more 

 interesting, and more valuable, received likewise a more 

 definite expression by which the natural as well as the 

 mental philosopher were enabled to connect facts 

 which before seemed unconnected, and to give to 

 their descriptions and classifications a deeper meaning; 

 enabling them also to some extent to know beforehand 

 in which direction to look for the discovery of new and 

 significant facts and phenomena. This second step may 

 57. be identified with Charles Darwin's work and the 



Darwin and 



appearance in the year 1859 of the 'Origin of 

 Species.' 



The title of this epoch-making book was not with- 

 out ambiguity; for, in the course of the diffusion and 

 criticism of the ideas contained in it, it has become 

 more and more evident that the process of natural 

 selection could not explain the origin of living matter, 

 but only the origin of separate species, the greater 

 differentiation which is continually going on in all 

 natural and mental processes. The genetic view of 

 natural phenomena has become limited to a genealogical 

 record, without being able to deal with first beginnings. 



