o conceive what motive can be in the mind of a cock, other
than that of making himself attractive, when he performs his various
antics, displays his ornamental plumes, or sings his melodious songs.
Considerations somewhat analogous apply to the difficulty of supposing
so much similarity and constancy of taste on the part of female animals
as Mr. Darwin's theory undoubtedly requires. Although we know very
little about the psychology of the lower animals, we do observe in many
cases that small details of mental organization are often wonderfully
constant and uniform throughout all members of a species, even where it
is impossible to suggest any utility as a cause.

Again, as regards the objection that each bird finds a mate under any
circumstances, we have here an obvious begging of the whole question.
That every feathered Jack should find a feathered Jill is perhaps what
we might have antecedently expected; but when we meet with innumerable
instances of ornamental plumes, melodious songs, and the rest, as so
many witnesses to a process of sexual selection having always been in
operation, it becomes irrational to exclude such evidence on account of
our antecedent prepossessions.

There remains the objection that the principles of natural selection
must necessarily swallow up those of sexual selection. And this
consideration, I doubt not, lies at the root of all Mr. Wallace's
opposition to the supplementary theory of sexual selection. He is
self-consistent in refusing to entertain the evidence of sexual
selection, on the ground of his antecedent persuasion that in the great
drama of evolution there is no possible standing-ground for any other
actor than that which appears in the person of natural selection. But
here, again, we must refuse to allow any merely antecedent presumption
to blind our eyes to the actual evidence of other agencies having
co-operated with natural selection in producing the observed results.
And, as regards the particular case now before us, I think I have shown,
as far as space will permit, that in the phenomena of decorative
colouring (as distinguished from merely brilliant colouring), of
melodious song (as distinguished from merely tuneless cries), of
enormous arborescent antlers (as distinguished from merely offensive
weapons), and so forth--I say that in all these phenomena we have
phenomena which cannot possibly be explained by the theory of natural
selection; and, further, that if they are to