INTKODUCTION xxi 



higher and lower ideas. Man cannot be undergoing 

 these mental struggles for nothing ; and therefore we 

 must admit the probability of a future mental exis- 

 tence, although it may be beyond the power of our 

 intellect to conceive it. 



1 think that this lesson of evolution will in 

 time be believed in by everyone, as implicitly as we 

 believe in the revolution of the earth round the sun ; 

 and that thus the theory of evolution will also be- 

 come one of the foundations of our theological beliefs. 



