INTRODUCTION 11 



of the theories of causality and evolution to our re- 

 cently acquired knowledge, insufficiently elaborated 

 as yet, presents many difficulties: our mind has not 

 been in possession of these new ideas long enough to 

 know how to handle them unerringly. 



It is not our province to touch upon questions 

 to which the evolutionist method may only be applied 

 in a more or less remote future. We have only al-> 

 hided to them in order to illustrate the far-reaching 

 import of the evolutionist idea. 



For this idea we are indebted to natural science; 

 neither transcendental philosophy, nor the exact sci- 

 ences would have fathered it or assured its triumph. 

 It is within the domain of natural science, its special 

 province, that we will study the idea of evolution in 

 the course of the following chapters. 



There it rules without a rival and the only points 

 raised concern the very processus of the evolution of 

 living things and the factors which have determined 

 the successive transformations of the various species. 



