She can act on every internal organ, on every shade of
constitutional difference, on the whole machinery of life. Man selects
only for his own good; Nature only for that of the being which she
tends. Every selected character is fully exercised by her; and the
being is placed under well-suited conditions of life. Man keeps the
natives of many climates in the same country; he seldom exercises each
selected character in some peculiar and fitting manner; he feeds a
long and a short beaked pigeon on the same food; he does not exercise
a long-backed or long-legged quadruped in any peculiar manner; he
exposes sheep with long and short wool to the same climate. He does
not allow the most vigorous males to struggle for the females. He does
not rigidly destroy all inferior animals, but protects during each
varying season, as far as lies in his power, all his productions. He
often begins his selection by some half-monstrous form; or at least by
some modification prominent enough to catch his eye, or to be plainly
useful to him. Under nature, the slightest difference of structure or
constitution may well turn the nicely-balanced scale in the struggle
for life, and so be preserved. How fleeting are the wishes and efforts
of man! how short his time! and consequently how poor will his
products be, compared with those accumulated by nature during whole
geological periods. Can we wonder, then, that nature's productions
should be far "truer" in character than man's productions; that they
should be infinitely better adapted to the most complex conditions of
life, and should plainly bear the stamp of far higher workmanship?
It may be said that natural selection is daily and hourly
scrutinising, throughout the world, every variation, even the
slightest; rejecting that which is bad, preserving and adding up all
that is good; silently and insensibly working, whenever and wherever
opportunity offers, at the improvement of each organic being in
relation to its organic and inorganic conditions of life.
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