Decline and fall of the Galactic Empire
In his youth Isaac Asimov constructed three distinct major fictional universes, each thematically separate, the far future Foundation trilogy, the near future series of short stories about positronic robots, and an intermediate series about the conflict between Earthers and Spacers, the latter being potentially in the same universe as his earlier robot novels.
Much later, after a successful career as an author of non-fiction expository works on a wide variety of subjects, he wrote a sequel to the Foundation trilogy, "Foundation's Edge". Not content with this he embarked on a series of novels to tie his various universes together. Since his death the composite universe has been extended by authorized novels by David Brin and Greg Bear.
The time line for Isaac Asimov's composite universe:
EARLY (IN THE NEAR FUTURE)The theme of the original Foundation trilogy (a series of short stories and novellas packaged in three volumes)is the unfolding of a grand planned history, the Seldon plan, the threat of the plan being destroyed, and the plan being saved. The trilogy has its faults. Asimov was quite young at the time: His appreciation of the variety of human behaviour was limited and many of the details of his universe were quite naive in conception. The quality of his prose is subject to debate. The stories were somewhat dryly intellectual in conception. None-the-less there is a grandness of conception and intriguing puzzles. They also have one of his few great characters, the Mule. The real hero, however, of the trilogy is the Seldon plan itself. The Foundation stories are a triumph of science fiction as the literature of the idea as hero.The End of Eternity EARTH AND THE SPACERS
In his early years he wrote two excellent novels, The Caves of Steel and The Naked Sun, both sparse. They carried the robots of I, robot into a future of spacers vs Earth, the spacers having a mixed human/robot culture spread across many worlds and Earth a city based culture with a fear of robots. Earth is technologically backwards and its residents are psychologically restricted to their caves of steel. (The spacers vs Earth theme is an elaboration of an earlier novella, Mother Earth.) Both are detective stories in an SF setting. Both rely on two strong characters, the human detective, Lije Bailey and the human appearing robot, Daneel. A thesis of the novels is that the future of humanity lies in a C/Fe culture, i.e., in the equal partnership of human and robot.
Foundation's Edge was written many years later. His early novels was sparse; FE is the first of a series of bloated novels. In my opinion it is the first step in his disowning the Foundation trilogy. The entire basis of the character of the Mule is destroyed. The Seldon plan is disowned as being ultimately worthless and a cheap-jack psionic mysticism is offered in its place.
Having returned to the worlds of his youth, Asimov determined to unite his two grand universes. There are no robots in the Foundation universe so it was necessary to eliminate them. He did this in two more bloated novels, The Robots of Dawn and Empire and Robots. In these he disowns the thesis of the C/Fe culture. The spacers are discounted as not being viable; Daneel, on the other hand, is promoted into a mind-controlling demi-god. He followed these two with a third bloated novel, Foundation and Earth, a sequel to Foundation's Edge in which it is ultimately revealed that Daneel is the master mind behind human history.
This was, for the nonce, the capstone of his of his campaign to disown the work of his youth by rewriting the juice out of it. The value of the Seldon plan had been discounted; the Mule had been emasculated; Daneel had been destroyed by deification; and the C/Fe thesis had been discarded. He wasn't done.
Prelude to Foundation and the sequel Forward the Foundation are set on Trantor; nominally they are about how Hari Seldon brings about the Seldon plan. Both are farragos of implausible melodrama. Concealed within them however is the final discounting - the revelation that the Seldon plan was never feasible in the first place.  The Bear, Brin, et al novels are a continuation of the melodrama. In the words of bard, they are full of sound and fury, signifying nothing.
 The End of Eternity is not part of the series but it implicitly references it.
 The Stars Like Dust is an early work; it isn't quite consistent with his later works but is consistent with the earlier novels. It features a radioactive Earth whose radioactivity is due to a nuclear war.
 In Second Foundation the original plan was somewhat makeshift, a "best we can do" at the time job. The one sour note is the idea advanced in Second Foundation that the second foundation was to be the ruling class.
There is a fundamental problem with the psychohistory concept; the psychohistorians become the rulers and they, too, are human. Michael Flynn makes it all clear in In the Country of the blind. Asimov didn't come to terms with the issue in the Foundation trilogy; later on, in "Foundation's Edge" he confronted it but his solution was icky.
This page was last updated October 11, 1999.