This had been one of Hal’s deepest and most pregnant abstractions […] That we’re all lonely for something we don’t know we’re lonely for. How else to explain the curious feeling that he goes around feeling like he misses somebody he’s never even met? Without the universalizing abstraction, the feeling would make no sense. (Infinite Jest, p. 1053, note 281).
I think this a marvelous description of what I have called nostalgia, the condition for the sense of recollection of amnamnesis when one then meets the somebody one has not yet met.