Shut the door, they're coming through the window, shut the window, they're coming through the door," are the words to an old song. They fit my lifestyle with newly arriving butcher/censors every month. Only six weeks ago, I discovered that, over the years, some cubby-hole editors at Ballantine Books, fearful of contaminating the young, had, bit by bit, censored some 75 separate sections from the novel. Students, reading the novel which, after all, deals with censorship and book-burning in the future, write to tell me of this exquisite irony.