Lewis B. Smedes

When we forgive evil we do not excuse it, we do not tolerate it, we do not smother it. We look the evil full in the face, call it what it is, let its horror shock and stun and enrage us, and only then do we forgive it.

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.