the message that arrives before it can be read
a queasy feeling, not the glittery disorientation of nightmares or on-court panic but a soggier, more furtively nauseous kind of sense, as if someone had been reading mail of Hal’s that he thought he’d thrown away.
Context
Something is being transmitted to Hal about himself, through Québecois-history lectures he can't see the point of, and it reaches him as nausea before it reaches him as sense — a communication received pre-consciously, its content withheld from the very person it's about. The image is of privacy violated in reverse: not that he's read someone's mail, but that his own discarded interior has been read back to him by a channel he doesn't control.