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 
