Fantasy and science fiction are closely allied in publishing, since both categories posit worlds that are not reality. The SF editor is most often a fantasy editor as well. Yet the most useful view for the working editor is to consider fantasy as conservative and pastoral, and SF as radical, technological, urban. There is a spectrum of variations, especially considering that for at least the last half century, many of the same authors have written both, a legacy, again, of the pulp magazines, which published both in the early twentieth century, before the battle lines were clearly drawn.