I FUNDAMENTAL CONCEPTS 13 



ably from psychical or mental causes. Darwin called it Sex- 

 ual Selection, and in spite of the opposition of A. R. Wallace 

 and others not only attributed great importance to it, but 

 as time went on and he saw his great vision more clearly, 

 he gave it an ever-growing emphasis in his theory of Descent. 

 Natural Selection operates on the unfit by destroying them 

 or killing them off; Sexual Selection, on the contrary, has a 

 more limited operation and applies only in respect of males, 

 whose reproduction it handicaps, limits or prevents. In 

 other words it is a struggle among males for the possession 

 of females, and in this struggle males are assisted not only 

 by their superior strength or fighting powers, but also by 

 their superior power of song or beauty or scent or general 

 attractiveness or excitiveness to females. It is clear that the 

 real motive power of this form of selection is mostly biolog- 

 ical and psychical. The female is excited and attracted by 

 superior fighting force or superior artistic endowments 

 among males competing for her favour. And when one con- 

 siders the degree of perfection to which the male forms have 

 attained largely under this stimulus of the female sex in- 

 stinct, one is struck with amazement at the emotional sensi- 

 tiveness thus implied on the part of female insects, birds, and 

 beasts, and at the wonderful subtlety and fineness of the 

 emotional discrimination which has resulted from it. The 

 beauty of form and colour which characterises, for instance, 

 the peacock's feathers are such that even our human eye can 

 scarcely do justice to it. And yet on the principle of Sexual 

 Selection that perfection of beauty is due to the amazing 

 emotional sensitiveness and appreciation of the peahen, 

 which through countless generations must have been 

 attracted by the minute superfority of the one male over 

 others in this respect. And the same applies in regard to 

 the wonderful power of song among male birds and 

 all the other secondary male characters. The psychical 

 emotional powers implied on the part of the female on 

 this theory are so wonderful as to be almost unintelligible; 

 in many respects they are superhuman, and would appear 

 to throw an astonishing light on the unconscious psychical 



