Hilary Rhoda

Ireland, in breadth, and for wholesomeness and serenity of climate, far surpasses Britain; for the snow scarcely ever lies there above three days: no man makes hay in the summer for winter's provision, or builds stables for his beasts of burden... the island abounds in milk and honey.

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.