oo
frequent yielding to the sexual impulse."[179] Be that as it may, it
is, in any case, if we grant the facts, a means through which male
sexual behaviour with all its biological and psychological
implications, is raised to a level otherwise perhaps unattainable by
natural means, while in the female it affords opportunities for the
development in the individual and evolution in the race of what we may
follow Darwin in calling appreciation, if we empty this word of the
aesthetic implications which have gathered round it in the mental life
of man.

Regarded from this standpoint of sexual selection, broadly considered,
has probably been of great importance. The psychological
accompaniments of the pairing situation have profoundly influenced the
course of biological evolution and are themselves the outcome of that
evolution.

Darwin makes only passing reference to those modes of behaviour in
animals which go by the name of play. "Nothing," he says,[180] "is
more common than for animals to take pleasure in practising whatever
instinct they follow at other times for some real good." This is one
of the very numerous cases in which a hint of the master has served to
stimulate research in his disciples. It was left to Prof. Groos to
develop this subject on evolutionary lines and to elaborate in a
masterly manner Darwin's suggestion. "The utility of play," he
says,[181] "is incalculable. This utility consists in the practice and
exercise it affords for some of the more important duties of
life,"--that is to say, for the performance of activities which will
in adult life be essential to survival. He urges[182] that "the play
of young animals has its origin in the fact that certain very
important instincts appear at a time when the animal does not
seriously need them." It is, however, questionable whether any
instincts appear at a time when they are not needed. And it is
questionable whether the instinctive and emotional attitude of the
play-fight, to take one example, can be identified with those which
accompany fighting in earnest, though no doubt they are closely
related and have some common factors. It is probable that play, as
preparatory behaviour, differs in biological detail (as it almost
certainly does in emotional attributes) from the earnest of after-life
and that it has been evolved through differentiation and integration
of the primary tissue of experience, as a preparation through which
certain essential modes of