38 SSAYS SCIENTIFIC AND PHILOSOPHICAL. 



necessarily follow that his mental nature, even though 

 developed part passu with it, has been developed by the 

 same causes only." 



Certainly not ; but the burden of proof rests 

 with those who deny it. And it would seem as 

 if they were at least bound to show us how that 

 other "influence, law, or agency" works, which in 

 man, and man only, is supposed to supersede, 

 or assist, natural selection. Instead of this Mr. 

 Wallace emphasizes the difficulty of explaining 

 the mathematical, the musical, and the artistic 

 faculties, by natural selection, and then leaps to 

 the conclusion that they must have had some 

 origin " wholly distinct " from that which accounts 

 for the animal characteristics. 



What, then, is this "wholly distinct origin"? 

 Mr. Wallace apparently holds the view of " a 

 spiritual nature superadded to the animal nature 

 of man," and, of course, with this deus ex machind 

 he can account for everything, though he tells us 

 little or nothing of the law by which this spiritual 

 nature acts. But this idea of " superaddition " is 

 full of difficulties. It destroys the unity of man. 

 Instead of the "reasonable soul and flesh" being 

 " one man " we have a highly organized animal 

 with a " superadded spiritual nature." And then, 

 if we are to believe that a creature of the stock of 

 the anthropoids became a man by the superaddition 

 of a spiritual nature, is not a similar superaddition 



