''The End of Eternity'' is a science fiction book by Creator/IsaacAsimov.
The story is set in a world where TimeTravel is highly sophisticated. A group of people known as [[TheMenInBlack Eternals]] reside in a space outside of our normal reality, but linked to it via vehicles called Kettles. They recruit people from the normal timeline, and control the period from about the 25th Century to the 70,000th Century. Within this period, they are constantly making Reality Changes, which are used [[SetRightWhatOnceWentWrong to erase wars and technological advances deemed contrary to the human race]]. One of the main themes is that space-travel, a staple in Asimov's other science fiction works, has been repeatedly stomped out in order to preserve the status quo and keep mankind on Earth (not out of sheer malice - but because advances in space travel always seem to coincide with increased drug use, crime etc, so these advances are undone "for the greater good".).
Eternals are comprised of several groups - Sociologists, Technicians, Life-Plotters and Computers[[note]]"Computer" in this novel has its original meaning, "person employed to do computations". Electronic devices built to do computations are called Summators or computaplexes.[[/note]] are mentioned, in addition, there are also Maintenance people. Sociologists accumulate data and analyze it for possible Reality Changes. Computers narrow down when and where the Reality Change takes place, and the Technicians pinpoint and make the Reality Changes themselves. Because of this, Technicians are highly revered, yet feared. They are also supposed to suppress all emotion because of the nature of their job, and thus rarely find love.
The start of Eternity is explained to be a [[StableTimeLoop time paradox]]. The man who "discovered" time travel in Primitive times (before Eternity) wrote a journal. In the journal, he detailed his life, [[labelnote:spoiler - click to reveal]]in which he is trained by the main character and his Computer superior and sent back in time to restart the loop. The Computer superior knows all of this, but the main character and their trainee do not.[[/labelnote]]
The story revolves around Andrew Harlan, a particularly skilled Technician, and his role in the ending of Eternity. [[labelnote:Large spoilers - click to reveal]]The people who blocked Eternity's access to the future centuries after the 70,000th have discovered a different form of time travel, and used it to discover that in the far future, humanity no longer exists. The reason for this is that once they finally left Earth with space travel, they found the galaxy already populated by other species, and were thus restricted to Earth. Thus enclosed, they decayed and died. To correct this, they cut off Eternity's access to their Centuries to prevent Reality Changes from affecting them. They then decide to send a woman backward in time to undo Eternity and open the galaxy to humanity. The woman chooses Harlan as the key because through her study she came to love him, and because his scenario (the breaking of the loop) is the [[ResetButton easiest way to end Eternity]].[[/labelnote]]
The book, though relatively obscure (for a science fiction book written by Creator/IsaacAsimov), has achieved an interesting place in the minds of Foundation fans who [[BrokenBase either]] consider the TwistEnding to be the reason the Robots/Empire/Foundation series even ''began'' or others who (plausibly) claim that ''The End of Eternity'' is not part of the ''Foundation'' series's canon. The former seem to be the majority and considering how Asimov's fanbase still survives, it's strange that it took so long for the book to be printed again.
(If you're looking for the completely unrelated [=RPG=], that's on the wiki as ''VideoGame/ResonanceOfFate'', its English title.)
!!This work features examples of the following tropes:
* AlternateHistory: Several different versions of history occur over the course of the book, due to the interventions of the Eternals.
* AlwaysSomeoneBetter: Twissel.
* BecauseDestinySaysSo: [[spoiler:Twissel's]] justification for the StableTimeLoop.
* DoesThisRemindYouOfAnything: 10% of the people are busy with constantly rewriting the past, the other 90%, despite being looked down upon, are actually better off, you need a special permission for a relationship with a woman... Can we say Literature/NineteenEightyFour?
* DoubleMeaningTitle: The title initially appears to refer to Eternity's ''purpose'', the thing that supposedly justifies its means. It turns out to also refer to that which is the opposite of the Beginning of Eternity.
* EvolutionaryStasis: Discussed and arguably justified. Twissell, from beyond the 30,000th century, is virtually undistinguishable from a modern human (to make no mention of [[spoiler:Nöys]], who's from beyond the 100,000th century and still there's no way to tell). Twissell is convinced that this stagnation is due to some machination from beings in the future, but it's revealed that [[spoiler:Eternity itself]] has deprived mankind of any evolutionary drive.
* ForWantOfANail: The Eternals exploit this professionally and with mathematical precision. The book begins with the main character changing the course of history by moving a small object onto a different shelf.
* ForbiddenFruit: No˙s to Harlan.
* HeelFaceTurn: [[spoiler:Twissel]]
* HitlersTimeTravelExemptionAct: Subverted: [[spoiler:World War II did not end with a nuclear strike in their reality, but the heroes ''cause'' it by sending instructions to a scientist on how to create a nuclear bomb and prevent Eternity from ever forming.]]
* KnightsTemplar: Eternity.
* ManicPixieDreamGirl: No˙s [[spoiler:seems to be one at first, being a sexual free spirit that breaks Harlan out of his repressed shell, but this is repeatedly subverted over the course of the book. It turns out the reason she was interested in him was because of a rumor in her time that sleeping with an Eternal will make a girl immortal. But then she tells him that she actually was attracted to him, and the immortality, if true, would only have been a bonus. But THEN it is revealed she is actually one of the unknown far-future humans, who came back in time to manipulate Harlan into a position where he could unmake Eternity... but she actually is still in love with him (because she spent so much time studying him in preparation for her mission), and fully intends to live out her life with him in the past... if he doesn't kill her.]]
* PlaceBeyondTime: Eternity itself.
* PublicSecretMessage: A stranded time-traveller leaves a marker of his location by placing an advertisement in the paper constructed of references to a significant event that hasn't happened yet at the time he places the ad.
* RubberBandHistory: [[spoiler:The new history that is created at the end of the novel by the intervention of the Lost Century people is ours -- after all, our history books tells us the first detonation of an atomic bomb has happened, and was in 1945...]]
* ScienceMarchesOn: In fact, it's seen within the story, as [[spoiler:the people from the Lost Centuries have much more advanced time travel technology capable of blocking the Eternity's time travel and being able to extrapolate the effects of technology much farther into seeing multiple realities at once.]]
* ShinyLookingSpaceships: Eternity, in their quest to raise the sum total of happiness, keeps these from ever being made. In fact, they keep serious space travel from ever happening at all.
* StableTimeLoop: The whole story is about breaking one, but the characters don't realize there is one until late in the story.
* TheTimeTravellersDilemma: The whole point of the book.
* WeWillNotHaveAppendixesInTheFuture: This is actually a plot point.
* WhamEpisode: As is probably implied by the amount of spoiler tags on this page, the twist ending is one hell of a twist ending.
* YouWillBeBeethoven: Tied to the invention of the time machine.