A. J. Liebling

Vietnam helped me to look at the horror and terror in the hearts of people and realize how we can't aim guns and set booby traps for people we have never spoken a word to. That kind of impersonal violence mystifies me.

The historical novelist has to consider what has actually happened, while the SF writer is dealing in possibilities, but they are both in the business of imagining a world unlike our own and yet connected to it.