When Horace Gold suggested that he write a mystery about a detective with a robot partner, the result was The Caves of Steel, which Asimov set in an underground city that reflected his own preference for enclosed spaces. It was a major advance, and he followed it with The End of Eternity, his single best novel, as well as a secret repudiation of the Foundation series—it described a similar organization of scientists as a collection of “psychopaths.” Campbell turned it down.
