Francois de La Rochefoucauld

Work hard. I got tenure a year early. Junior faculty members used to say to me: 'Wow, what's your secret?' I said: 'It's pretty simple. Call me any Friday night in my office at 10 o'clock, and I'll tell you.'

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.