The Logic of Evolution 



tain or mere cloud and mist? We must prove 

 every step thoroughly if we would not fall into 

 error. 



Like begets like always, and still there is 

 always variation. So far as we can see, the 

 struggle for life is unending. Natural selection 

 still works steadily and relentlessly. Still the fit- 

 test survive. The method of working varies, 

 and the results of each process are always higher 

 and larger. This much seems fairly certain. 

 But we must study these forces or tendencies 

 carefully in the light of all the facts of human 

 structure and character before we can have an 

 adequate theory of human evolution. Other- 

 wise we may frame a hypothesis whose working 

 would have doomed man to stagnation in brute- 

 hood, if not to degeneration and extinction. 



