i MENTAL EVOLUTION n 



changes of such a kind as are now known to be compatible 

 with the working of heredity may sum themselves up into 

 a distinct change of quality need occasion no surprise. 

 We all know that in the individual bony and muscular 

 tissue alike arise out of an original undifferentiated mass 

 of protoplasm. Yet bone is one thing and muscle another 

 and the protoplasm of a fertilised ovum a third, and 

 if these things are not qualitatively different, the term 

 quality has no meaning. In the same way we shall see 

 grounds for thinking that the reason of man differs in kind 

 from the intelligence of the dog, and the intelligence of 

 the dog differs in kind from the blind gropings of a polyp 

 without proceeding to infer that no course of development 

 could ever have produced the one type from the other. 

 The truth is that it is only when we admit and emphasise 

 qualitative distinctions that we arrive at the full sense of ^ 

 what development means and what it can do. It is the 

 natural tendency of an evolutionary theory in its first phase 

 when struggling for existence to pare away and depreciate 

 the distinctive features of the most highly developed and 

 peculiar structures which it has to explain, to bring them 

 as nearly as it can to the level from which development 

 is to start. This is the natural protective device of an 

 infant theory threatened by enemies in the shape of pre- 

 judice and incredulity. The time has gone by when 

 evolutionary theories stood in need of such adventitious 

 and indeed slippery and uncertain aids. We can surely 

 afford now to look the facts steadily in the face and faith- 

 fully report the actual scope of mind-development as we 

 find it. 



From this study then there emerges as the principal 

 result the recognition of certain qualitative changes which 

 vitally affect our interpretation of the process of human 

 evolution, its genesis, its potentialities and its permanent 

 conditions. The sum and substance of these changes is 

 to effect a complete revolution in the position of mind as 

 it exists in living beings. Coming into existence as the 

 biologist has told us as a means of securing the permanence 

 of the species it never loses that function, and indeed comes 

 to perform it more efficiently. But it ceases to be limited 



