4 Heredity and Social Progress 



are as old as themselves. Wealth does not 

 endure, but is constantly replaced from the 

 annual produce. The real source of progress 

 must, therefore, lie in the acquisition of mental 

 traits ; even permanent improvements are of 

 little avail until a mental trait arises which 

 causes them to be appreciated. 



The situation, then, is this: the natural sur- 

 plus is steadily decreasing, or at best it merely 

 holds its own ; the social surplus is the result 

 of conscious effort, which must so arouse men- 

 tal traits that natural decreasing returns be- 

 come socially increasing returns. How, then, 

 is the social surplus, the temporary product of 

 annual effort, transformed into mental traits 

 that abide and become the basis of subsequent 

 progress ? 



This is the problem stated in terms of eco- 

 nomics. The same problem arises in biology, 

 and, as there stated, is : How can acquired 

 characters become natural? Notice that the 

 two questions involve the same points. The 

 social surplus is a consciously created prod- 

 uct: it is made by effort after men arrive 

 at maturity. Economic traits are thus ac- 



