SEX AND SOCIAL RELATIONS 231 



this alone, which gives a biological sanction to the 

 interference with natural tendencies in population. 



The case of large countries with a swarming popu- 

 lation and low standards of living must also be con- 

 sidered in estimating the effects of small families in 

 more highly civilized neighboring countries. The 

 "yellow peril" which threatens Europe has loomed 

 large for many a generation. Will the Chinese try 

 to invade the western strongholds of civilization? 

 And if so, can their numberless hordes be success- 

 fully checked by the inferior numbers of the more 

 cultured nations? Every one is entitled to a pre- 

 diction on these momentous possibilities, but it is 

 doubtful if the greatest living statesmen have at 

 command the data to enable them to make predic- 

 tions worthy of credence. It is likely that the 

 risks of Mongolian invasion have been considerably 

 exaggerated. The nations of the West, though 

 inferior in numbers, have a relatively high level of 

 intelligence, far more imagination, and an incom- 

 parably greater capacity for rapid adaptation to 

 new conditions. These are qualities which must 

 powerfully influence the outcome in any conflict be- 

 tween the highly organized and disciplined forces of 

 the West and the heterogenous hordes of Cathay. 



But it is quite aside from the purpose of this 

 chapter to speculate on the international aspects of 

 the question of human population. I wish merely 

 to indicate that there are important international 

 phases of the question which may perhaps modify 



