RABBIT AT REST
by John Updike
Knopf; 512 pages; $21.95
"You might say it's a depressed book about a depressed man, written by a depressed man." That is how John Updike described his forthcoming novel, Rabbit at Rest, to a convention of booksellers in June. Some of his market- minded listeners may have wondered if they could find some way that the book could be pitched as anything but . . . depressing. There was no need to worry. This fourth, and presumably final, installment of the life and times of Harold C. Angstrom -- Rabbit Run (1960), Rabbit Redux (1971),...