Guillermo Cabrera Infante

My mother had been educated at a convent, and she had been converted to communism by my father during Stalin's most rampant period, at the beginning of the 1930s. So she had two gods, God in heaven and god on earth.

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.