124 EVOLUTION, OLD AND NEW. 



Taking the earth as a whole, and the human race in its 

 entirety, the numbers of mankind, like those of animals, 

 should remain nearly constant throughout time; for 

 they depend upon an equilibrium of physical causes 

 which has long since been reached, and which neither 

 man's moral nor his physical efforts can disturb, inas- 

 much as these moral efforts do but spring from physical 

 causes, of which they are the special effects. No 

 matter what care man may take of his own species, he 

 can only make it more abundant in one place by 

 destroying it or diminishing its numbers in another. 

 When one part of the globe is overpeopled, men emi- 

 grate, spread themselves over other countries, destroy 

 one another, and establish laws and customs which 

 sometimes only too surely prevent excess of population. 

 In those climates where fecundity is greatest, as in 

 China, Egypt, and Guinea, they banish, mutilate, sell, 

 or drown infants. Here, we condemn them to a per- 

 petual celibacy. Those who are in being find it easy to 

 assert rights over the unborn. Kegardiug themselves 

 as the necessary, they annihilate the contingent-, and 

 suppress future generations for their own pleasure and 

 advantage. Man does for his own race, without per- 

 ceiving it, what he does also for the inferior animals : 

 that is to say, he protects it and encourages it to in- 

 crease, or neglects it according to his sense of need 

 according as advantage or inconvenience is expected as 

 the consequence of either course. And since all these 

 moral effects themselves depend upon physical causes, 

 which have been in permanent equilibrium ever since 

 the world was formed, it follows that the numbers of 



