IDIOSYNCRASY. 391 



ing compromise between the two diverse heredities, the one seems 

 largely to prevail over the other in certain parts, yet it is difficult to 

 suppose that there is not a minute interrelation between all the parts : 

 and perhaps the significant fact that every mulatto, though darker or 

 lighter, is at least brown, not purely black or purely white, gives us 

 the best key to the true nature of the situation. 



So far, I have been tacitly but intentionally taking for granted the 

 very principle which I set out to prove, in order fully to put the reader 

 in possession of the required point of view. The question now arises, 

 Where in this series of events is there room for any fresh element to 

 come in ? Can any man ever be anything other than what some of 

 his ancestors have been before him ? And, if not, how is progress or 

 mental improvement possible? That men have as a matter of fact 

 risen from a lower to a higher intellectual position is patent. That 

 some races have outstripped other races is equally clear. And that 

 some individual men have surpassed their fellows of the same race and 

 time is also obvious. How are we to account for these facts without 

 admitting that new elements do at sundry times creep in by chance, in 

 the false and unphilosophical sense of the word ? How can we get ad- 

 vance unless we admit that exceptional children may be born from 

 time to time with brains of exceptional functional value, wholly un- 

 caused by antecedents in any way ? 



The answer to this question is really one of the most important in 

 the whole history of mankind. For on the solution of the apparent 

 paradox thus propounded depend two or three most fundamental ques- 

 tions. It is by this means alone that we can account, first, for the exist- 

 ence of great races like the Greeks or the Jews. It is by this means 

 alone that we can account, secondly, for genius in individuals. And 

 it is by this means alone that we can account, thirdly, for the possi- 

 bility of general progress in the race. It is surprising, therefore, that 

 the question has so little engaged the attention of evolutionary psy- 

 chologists at the present day. 



There are only two conceivable ways in which any increment of 

 brain-power can ever have arisen in any individual. The one is the 

 Darwinian way, by "spontaneous variation" — that is to say, by varia- 

 tions due to minute physical circumstances affecting the individual in 

 the germ. The other is the Spencerian way, by functional increment 

 — that is to say, by the effect of increased use and constant exposure 

 to varying circumstances during conscious life. I venture to think 

 that the first way, if we look it clearly in the face, will be seen to bo 

 practically unthinkable : and that we have therefore no alternative but 

 to accept the second. Deeply as I feel the general importance of Dar- 

 win's theory of " spontaneous variation " (using the words in the sense 

 in which he always used them), it seems to me that that theory can 

 not properly be applied to the genesis of a nervous system, or of any 

 part of a nervous system, and that in this case we must rather come 



