is--purely an affair of the percipient
mind itself, depending on the association of ideas with pleasure-giving
objects. This association may well lead to a liking for such objects,
and so to the formation of what is known as aesthetic feeling with regard
to them. Moreover, beauty of inanimate nature must be an affair of the
percipient mind itself, unless there be a creating intelligence with
organs of sense and ideals of beauty similar to our own. And, apart from
any deeper considerations, this latter possibility is scarcely entitled
to be regarded as a probability, looking to the immense diversities in
those ideals among different races of mankind. But, be this as it may,
the scientific problem which is presented by the fact of aesthetic
feeling, even if it is ever to be satisfactorily solved, is a problem
which, as already remarked, must be dealt with by psychologists. As
biologists we have simply to accept this feeling as a fact, and to
consider how, out of such a feeling as a cause, the beauty of organic
nature may have followed as an effect.

Now we have already seen how the theory of sexual selection supposes
this to have happened. But against this theory a formidable objection
arises, and one which I have thought it best to reserve for treatment in
this place, because it serves to show the principal difference between
Mr. Darwin's two great generalizations, considered as generalizations in
the way of mechanical theory. For while the theory of natural selection
extends equally throughout the whole range of organic nature, the theory
of sexual selection has but a comparatively restricted scope, which,
moreover, is but vaguely defined. For it is obvious that the theory can
only apply to living organisms which are sufficiently intelligent to
admit of our reasonably accrediting them with aesthetic taste--namely, in
effect, the higher animals. And just as this consideration greatly
restricts the possible scope of the theory, as compared with that of
natural selection, so does it render undefined the zoological limits
within which it can be reasonably employed. Lastly, this necessarily
undefined, and yet most important limitation exposes the theory to the
objection just alluded to, and which I shall now mention.

The theory, as we have just seen, is necessarily restricted in its
application to the higher animals. Yet the facts which it is designed to
explain are not thus restricted. For beauty is by no means restricted