An Animal Imagined by C.S. Lewis: Chapter 5

Copper, Pennywhistle, Black Cotton Thread, Bells

The singing beast is one of the tough ones. He is described only as a sound.

Borges ads no comment, only including a passage from C.S. Lewis' Perelandra. Here's a bit of it:
"The noise was very loud now and the thicket very dense so that he could not see a yard ahead, when the music stopped suddenly. There was a sound of rustling and broken twigs and he made hasitly in that direction, but found nothing. He has almost decided to give up the search  when the song began again a little farther away. Once more he made after it; once more the creature stopped singing and evaded him. He must have played thus hide and seek with it for the best part of an hour before his search was rewarded... The head was in profile from where Ransom stood- the mouth wide open as it sang of joy in thick0-coming trills, and the music almost visibly rippled in its glossy throat..."

There is also a referance to "fawn like shyness" and "its evident wish to be forever a sound and only a sound".

That last bit is what stuck with me. It seemed a shame to make such a beast into a static object. At first, i wanted it to hide wholly behind bells, later, the whistle seemed to not need hiding, and, finally, I did not hide him completely, allowing him in his shyness to peak out at us, his audience.

The whistle is fully playable.