A stunning contemporary choral piece

I was driving home from work in the dark early evening of winter in upstate New York, with the radio on, when I heard this hauntingly beautiful choral piece. I arrived home, but had to sit in the car, engine off, radio on, to hear the last few chords of the song fading in the dusk. Thank you, Eric Whitacre, for that composition, and thank you, Polyphony, for a reverent performance of the piece.