What you were preparing against—that never happened! All the best-laid plans could not prevent the disaster against which no plans had been laid. - George R. Stewart

He had kept the university library as a reserve for the future. He had even taught the children to respect it. Yes, he had even, he was afraid, put a kind of taboo upon it. In fact, not only here but everywhere, he had always tried to impress the children with an almost mystical value of books. Still he kept the symbol of the burning of the books as one of the worst things that men could do.

How then, once overthrown, shall this great civilization, except by renewed Forces and Pressures, ever come again?

It has never happened!" cannot be construed to mean, "It can never happen!"—as well say, "Because I have never broken my leg, my leg is unbreakable," or "Because I've never died, I am immortal.