THE ACQUIREMENTS OF THE NORMAL MAN 389 



organisms, and so delicate the adjustment of their parts and 

 faculties,that many thinkers have been driven, in spite of the fact that 

 there is apparently no alternative, to doubt whether Natural Selec- 

 tion is adequate for the task. Our faith is restored only when 

 we contemplate the special and beautiful devices which Natural 

 Selection has evolved to help its work of adaptation and co- 

 adaptation on the one hand, bi-parental reproduction and the 

 tendency of retrogressive variations to preponderate over pro 

 gressive variations, both of which automatically plane away all 

 redundancies ; and, on the other, the power of developing under the 

 stimulus of use which brings about co-adaptation in the characters 

 of the individual through the influence which related parts and 

 faculties exercise over one another's growth. 



646. Again we have seen how much neglected has been the 

 study of ' acquirements ' ; it has even been supposed that evolution 

 is founded entirely on ' inborn' traits. But consider what man 

 would be without his mental acquirements. The congenital idiot 

 and the normal man start life equal, except in one particular. The 

 idiot has little or no memory, no power of learning, no power of 

 growing mentally under the stimulus of experience, whereas the 

 normal man has that power. This, at birth, is the sole difference 

 between the two. 1 But an empty memory, a mere possibility of 

 learning, is nothing. If the normal man had not filled his memory, 

 he also would be an idiot. Now is, or is not, the intelligence of 

 the normal man, which has arisen only because he, personally, has 

 made acquirements, a product of evolution ? Is not this mental 

 growth, which consists entirely in acquirements, and which 

 separates him mentally from such animals as the idiot and the 

 caterpillar, as much a part of his normal growth as his head or 

 his instincts ? If it is, then surely, the study of acquirements, 

 including the entire field of the intellect, is at least as well worth the 

 attention of the student of nature as the study of any other class 

 of character. 



647. It may be argued that 'the task of the biologist is 

 complete when he has traced the growth of memory, which is all 

 that is inborn, and, therefore, all that has undergone evolution.' 

 But to this there are two sufficient answers. First, no serious 

 attempt has ever been made to trace the evolution of memory. 

 Though it is the foundation of all intelligence, it has, of all mental 

 characters, been the most neglected by biologists in general and 

 psychologists in particular. Indeed to this day there are some 



1 See 762, et seq. 



