Nearly all the writing of our time is likely to disappear in a hundred years. Certainly most readers - and nearly all critics - feel that [Kurt] Vonnegut started to repeat himself, to grow increasingly self-indulgent and meandering, and to sometimes just blather in his later work. But his books up to "Slaughterhouse-Five" do possess a distinctiveness that will insure some kind of permanence, if only in the history of the 1960s and of science fiction.