MENTAL EVOLUTION OF MAN 233 



things he finds about him, or learns from others with- 

 out having to invent or originate them himself. Thus 

 a Zulu boy acquires the habits of a warrior and a 

 huntsman w^hen he grows up in his native village, 

 although he would undoubtedly develop (juite different 

 aptitudes if he should be taken as an infant to a city 

 of white men. Nevertheless his mental machinery it- 

 self would be no less surely determined by heredity, 

 even though the things with which it dealt would be 

 provided by an alien environment. 



Our present knowledge of the nature and history of 

 human mentality enables us to learn many lessons that 

 have a direct practical value, although it is impossible 

 under the present limitations to give them the full 

 discussion they deserve. Starting from the dictum 

 that physical inheritance provides the mechanism of 

 intellect, education and training of any kind prove to 

 be effective as agents for developing hereditary quali- 

 ties or for suppressing undesirable tendencies. Just as 

 wdnd-strewn grains of wheat may fall upon rock and 

 stony soil and loam, to grow well or poorl}^ or not at 

 all according to their environmental situations, so chil- 

 dren with similar intellectual possibilities would have 

 their growth fostered or hampered or prevented by 

 the educational systems to which they were subjected. 

 But the common-sense of science demonstrates that 

 the mental qualities themselves could not be altered in 

 nature by the circumstances controlling their develop- 

 ment any more than the hereditary capal)ility of the 

 wheat grains to produce wheat would be altered by 

 the character of the ground upon which they fell. 

 Education and training thus find their sphere of use- 



