d therefore cannot be attributed to the agency of natural
selection. Now this fact of beauty in organic structures is a fact of
wide generality--almost as wide, indeed, as is the fact of their
utility. Mr. Darwin, therefore, suggested another hypothesis whereby to
render a scientific explanation of this fact. Just as by his theory of
natural selection he sought to explain the major fact of utility, so did
he endeavour to explain the minor fact of beauty by a theory of what he
termed Sexual Selection.

It is a matter of observation that the higher animals do not pair
indiscriminately; but that the members of either sex prefer those
individuals of the opposite sex which are to them most attractive. It is
important to understand _in limine_ that nobody has ever attempted to
challenge this statement. In other words, it is an unquestionable fact
that among many of the higher animals there literally and habitually
occurs a _sexual selection_; and this fact is not a matter of inference,
but, as I have said, a matter of observation. The inference only begins
where, from this observable fact, it is argued,--1st, that the sexual
selection has reference to an aesthetic taste on the part of the animals
themselves; and 2nd, that, supposing the selection to be determined by
such a taste, the cause thus given is adequate to explain the phenomena
of beauty which are presented by these animals. I will consider these
two points separately.

From the evidence which Darwin has collected, it appears to me
impossible to doubt that an aesthetic sense is displayed by many birds,
and not a few mammals. This of course does not necessarily imply that
the _standards_ of such a sense are the same as our own; nor does it
necessarily imply that there is any constant relation between such a
sense and high levels of intelligence in other respects. In point of
fact, such is certainly not the case, because the best evidence that we
have of an aesthetic sense in animals is derived from birds, and not from
mammals. The most cogent cases to quote in this connexion are those of
the numerous species of birds which habitually adorn their nests with
gaily coloured feathers, wool, cotton, or any other gaudy materials
which they may find lying about the woods and fields. In many cases a
marked preference is shown for particular objects--as, for instance, in
the case of the Syrian nut-hatch, which chooses the iridescent wings of
insects, or that of the great cres