John Buchanan Robinson

Capital, however capital may be defined, would practically cease to exist as an income producing fund, for the simple reason that if money, wherewith to buy capital, could be obtained for one-half of one per cent, capital itself could command no higher price.

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.