SELECTION ON MAN. 309 



nourishing food to keep up the heat of the system. 

 Our supposed perfect animal is no longer in harmony 

 with its universe ; it is in danger of dying of cold or 

 of starvation. But the animal varies in its offspring. 

 Some of these are swifter than others they still 

 manage to catch food enough; some are hardier and 

 more thickly furred they manage in the cold nights to 

 keep warm enough ; the slow, the weak, and the thinly 

 clad soon die off. Again and again, in each succeed- 

 ing generation, the same thing takes place. By this 

 natural process, which is so inevitable that it cannot 

 be conceived not to act, those best adapted to live, live ; 

 those least adapted, die. It is sometimes said that we 

 have no direct evidence of the action of this selecting 

 power in nature. But it seems to me we have better 

 evidence than even direct observation would be, because 

 it is more universal, viz., the evidence of necessity. 

 It must be so ; for, as all wild animals increase in a 

 geometrical ratio, while their actual numbers remain 

 on the average stationary, it follows, that as many die 

 annually as are born. If, therefore, we deny natural 

 selection, it can only be by asserting that, in such a 

 case as I have supposed, the strong, the healthy, the 

 swift, the well clad, the well organised animals in 

 every respect, have no advantage over, do not on the 

 average live longer than, the weak, the unhealthy, the 

 slow, the ill-clad, and the imperfectly organised indi- 

 viduals ; and this no sane man has yet been found 

 hardy enough to assert. But this is not all ; for the 

 offspring on the average resemble their parents, and 



