Thus it would seem probable that, contrary to a belief once widely
prevalent, the sexual instinct has increased rather than diminished with
the growth of civilization. This fact was clear to the insight of
Lucretius, though it has often been lost sight of since.[225] Yet even
observation of animals might have suggested the real bearing of the facts.
The higher breeds of cattle, it is said, require the male more often than
the inferior breeds.[226] Thorough-bred horses soon reach sexual maturity,
and I understand that since pains have been taken to improve cart-horses
the sexual instincts of the mares have become less trustworthy. There is
certainly no doubt that in our domestic animals generally, which live
under what may be called civilized conditions, the sexual system and the
sexual needs are more developed than in the wild species most closely
related to them.[227] All observers seem to agree on this point, and it is
sufficient to refer to the excellent summary of the question furnished by
Heape in the study of "The 'Sexual Season' of Mammals," to which reference
has already been made. He remarks, moreover, that, "while the sexual
activity of domestic animals and of wild animals in captivity may be more
frequently exhibited, it is not so violent as is shown by animals in the
wild state."[228] So that, it would seem, the greater periodicity of the
instinct in the wild state, alike in animals and in man, is associated
with greater violence of the manifestations when they do appear. Certain
rodents, such as the rat and the mouse, are well known to possess both
great reproductive power and marked sexual proclivities. Heape suggests
that this also is "due to the advantages derived from their intimate
relations with the luxuries of civilization." Heape recognizes that, as
regards reproductive power, the same development may be traced in man: "It
would seem highly probable that the reproductive power of man has
increased with civilization, precisely as it may be increased in the lower
animals by domestication; that the effect of a regular supply of good
food, together with all the other stimulating factors available and
exercised in modern civilized communities, has resulted in such great
activity of the generative organs, and so great an increase in the supply
of the reproductive elements, that conception in the healthy human female
may be said to be possible almost at any time during the reproductive
period."
"People of sense and reflection are most apt to have violent and constant
passions," wrote Mary Wollstonecraft, "and to be preyed on by them."[229]
It is that fact which leads to the greater importance of sexual phenomena
among the civilized as compared to savages. The conditions of civilization
increase the sexual instinct, which consequently tends to be more
intimately connected with moral feelings. Morality is bound up with the
development of the sexual instinct. The more casual and periodic character
of the impulse in animals, since it involves greater sexual indifference,
tends to favor a loose tie between the sexes, and hence is not favorable
to the development of morals as we understand morals. In man the
ever-present impulse of sex, idealizing each sex to the other sex, draws
men and women together and holds them together. Foolish and ignorant
persons may deplore the full development which the sexual instinct has
reached in civilized man; to a finer insight that development is seen to
be indissolubly linked with all that is most poignant and most difficult,
indeed, but also all that is best, in human life as we know it.