In 1982 Isaac Asimov returned to the science-fiction world of the 1940s to produce the long-awaited fourth volume of the Foundation series [Foundation's Edge]. Reasons (of many kinds) for a sequel have been clear for many years; most important of them, the Trilogy itself stopped after 400 years of the thousand-year saga envisioned in Hari Seldon's psychohistorical predictions, and concluded with some uncertainty about the situation in which it left the Foundation universe. (p. 15)

[A brief summary of Foundation's Edge would give] little suggestion of the flavor of the novel. In style it belongs to the 1940s—not simply to science fiction's 1940s but to Asimov's 1940s. It is no novel of character—not even a Caves of Steel or a Gods Themselves—but a discursive novel of ideas, much like the rest of the Foundation stories As the first extended treatment …—in fact the longest novel Asimov has written...