Music doesn't represent any tangible, earthly reality. It represents things of the heart, feelings which are beyond description, beyond any experience one has had. The non-representational but indescribably vivid emotional quality is such as to make one think of an immaterial or spiritual world. I dislike both of those words, because for me, the so-called immaterial and spiritual is always vested in the fleshly — in "the holy and glorious flesh," as Dante said.
So if music is not directly representative of the world around us, then what's inspiring it? One has the feeling of the muse, and the muses are heavenly beings. This feeling is very, very strong with Cicoria, the surgeon in my book who was hit by a bolt of lightning. He felt that he was actually tuning in to the music of heaven — that he had God's phone number. I can't avoid that feeling myself when I listen to Mozart. I feel differently about Beethoven. I think of Beethoven as a sweating Prometheus, a terrestrial figure.
I intensely dislike any reference to supernaturalism, but I think there can be profound mystical feelings which do not have to call on fictitious agencies like angels and demons and deities. The whole natural world is bathed in wonder and beauty and mystery. The feeling of the holy, the sacred, the wonderful, the mystical, can be divorced from anything theological, and is conveyed very powerfully in music.
And here's the Sacks iPod playlist.