You have a knack for turning your eyes inside out, so you see them. And they see you. And you're afraid, because they're from the uncreated future, from a place, I think, where the human race has reached its last incarnation, from the end of the material world. Perhaps the end of all worlds. And they're sad—melancholy is the better word—because you're like an angel to them, the angel of the past, the angel of infinite possibility. Possibility lost. The road not taken.

The Observer (p. 111) - The Perseids and Other Stories (2000)