Gately, the wraith, and the figurants — "The wraith said Even a garden-variety…"
The wraith said Even a garden-variety wraith could move at the speed of quanta and be anywhere anytime and hear in symphonic toto the thoughts of animate men, but it couldn’t ordinarily affect anybody or anything solid, and it could never speak right to anybody, a wraith had no out-loud voice of its own, and had to use somebody’s like internal brain-voice if it wanted to try to communicate something, which was why thoughts and insights that were coming from some wraith always just sound like your own thoughts, from inside your own head, if a wraith’s trying to interface with you.
Context
The wraith-physics master statement: quanta-speed, total telepathic hearing, no solidity, no voice — and the brain-voice rule that retro-infects the whole novel, since any "little voice inside" anywhere in the book may now have been somebody else. This is the theme's center of gravity; everything else in this collection orbits it.