On the other hand, I willingly admit that a great number of male animals, as all our most gorgeous birds, some fishes, reptiles, and mammals, and a host of magnificently coloured butterflies, have been rendered beautiful for beauty's sake.

But this has been effected through sexual selection, that is, by the more beautiful males having been continually preferred by the females, and not for the delight of man.

So it is with the music of birds.