The Happiest of the Poets in Ideas of Good and Evil by William Butler Yeats.

“The desire seems not other than the desire of the bird for its mate in the heart of the wood, and we listen to that joyous praise as though a bird watching its plumage in still water had begun to sing in its joy, or as if we heard hawk praising hawk in the middle air, and because it is the praise of one made for all noble life and not for pleasure only, it seems, though it is the praise of the body, that it is the noblest praise.” [via]