David Ogilvy

I think, when I was younger, I was cooking to impress. Sometimes the dish would have 15 things on the plate. That's cooking only for yourself. As you get more mature, you take all the superfluous things away, and you get the essential flavor. Now I cook for people, not for myself.

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.