" We must assume, I think, that
the forward projection of what imagination he had, stopped at the act, on the brink of
all its possible consequences; ghost consequences, comparable to the ghost toes of an
amputee or to the fanning out of additional squares which a chess knight (that skips-pace piece), standing on a marginal file, "feels" in phantom extensions beyond the
board, but which have no effect whatever on his real moves, on the real play. "

― Vladimir Nabokov , Pale Fire