The Foundation Trilogy

A landmark of science fiction's "Golden Age," Isaac Asimov's Foundation Trilogy--which comprises the novels Foundation, Foundation and Empire, and Second Foundation - has long been regarded a visionary masterpiece whose astonishing historical scope perfectly conveys science fiction's sense of wonder.
First published as a cycle of stories in the 1940s and '50s, Asimov's iconic trilogy has endured to become, like the author himself, a legend of science fiction.

Set in the far future, Foundation envisions a Galactic Empire that has thrived for 12,000 years, but whose decline into an age of barbarism lasting some thirty millennia is imminent - if the predictions of renegade psycho-historian Hari Seldon are accurate.
Hoping to shorten the interval of this impending new Dark Age, Seldon convinces the Empire's Commission of Public Safety to allow him enact a diversionary plan - one full of surprising subterfuges and intrigues intended to create and protect a Foundation on which the future Empire will be erected.

Foundation and Empire advances the story farther into the future, in which a technologically advanced Foundation triumphs over attacking forces of the collapsing Empire. Yet even as the Foundation emerges valiantly, in fulfillment of Hari Seldon's scheme, at the far corners of the Empire a powerful mutant, whose existence was never accounted for in Seldon's projections, emerges to overwhelm the Foundation and establish his own tyrannical version of the Empire.
In Second Foundation, a new Second Foundation, whose whereabouts have been kept secret from the original Foundation for safety's sake, asserts itself as the true fulfillment of Hari Seldon's plans for the Empire--and thereby pits itself against a Foundation resentful of its usurped authority.