Henry David Thoreau

When I - when I was going to school, I knew how to read, write, add and subtract and I - I basically said, 'What else do I need? I'm never going to be able to go to college. I'm not going to be able to afford to go to college. I'm not going to be able to get a scholarship.'

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.