Robert E. Howard

Never the less, it is no light thing to enter into a profession absolutely foreign and alien to the people among which one's lot is cast; a profession which seems as dim and faraway and unreal as the shores of Europe.

People didn't just wear wedding dresses in the past. They also wore plain cotton shifts beneath them. As pretty as the dresses might be, and as lovely as they might look on display, if a museum doesn't hang the shifts beside them or acknowledge that the shifts existed, that exhibit's incomplete.

When a herd of cattle see a strange object, they are not satisfied till each one has sniffed it; and the horse is cured of his fright at the robe, or the meal-bag, or other object, as soon as he can be induced to smell it. There is a great deal of speculation in the eye of an animal, but very little science.

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.