The End of Eternity concerns Andrew Harlan, a Technician for the organization called Eternity. As a Technician, Harlan is an expert at determining and executing the Minimum Necessary Change in a timeline to attain a desired Change in history. For the Eternals, men who live "outside Time," monitor human history from the 27th century to about the 70,000th century, trying to maintain a stable society, with reasonable prosperity. They allow some trade between centuries, but for the most part they work at eliminating worrisome trends: excessively unusual social mores, dangerous technology such as atomic weapons, and, to be sure, excessive curiosity about the nature of Eternity.

As the book opens Harlan is shown committing a crime: in exchange for concealing a minor error by a functionary of one of the Eternity bases, he arranges to have the Life Plot of a certain woman tracked through a change. For, you see, when Reality Changes, everybody changes with it. And a woman you loved might suddenly be married, or have suffered an accident, or be altered in personality.

Flashbacks then show Harlan's history: his recruitment from a somewhat conservative century, his early career as an Eternal, his interest in Primitive history (from before the invention of time travel, thus before Eternity can manipulate history). Finally he encounters the alluring Noÿs Lambent, a woman of a sexually loose century, and the stiff, inexperienced Harlan falls in love, and before long is ready to risk the very existence of Eternity to keep his woman.

Asimov resolves his story, as I've said, fairly cleverly, in the process giving us a look at the creation of Eternity, and at the Hidden Centuries so far in the future that the Eternals can't penetrate, or aren't allowed to penetrate. He makes use of time paradoxes worthy of Charles Harness, but Asimov's presentation is so deadpan and rationalistic that he almost makes them believable. And in the end, he asks whether stability and general happiness is the most worthwhile goal. His answer is the expected answer for a Campbell-nurtured writer of the 50s, but it's still the answer I'd give, with modifications. (After all, Asimov's ideal vision, as presented in this book and elaborated in his Foundation/Empire books, is of a human-dominated galaxy. In essence, he suggests, we need to get to the stars before They -- the aliens -- do. Surely it's better that we get to the stars along with Them?)

Upon rereading The End of Eternity I'd still call it Asimov's best novel. If his picture of an all-male Eternity (admittedly given at least nominal justification in the book) seems risible from a contemporary perspective, so does much 50s SF fail in treatment of women. So too his sex scenes and love scenes are awkward (and the book does have a sex scene, albeit a very discreet one, despite Asimov's habit of joking that he didn't write about sex until he wrote about alien sex in The Gods Themselves): but 50s SF writers were rarely allowed much practice in that area. The ideas presented in the book are still compelling: the meta-society of Eternity is nicely worked out, with many cute details, and the overarching theme is well-argued, and still merits thought. And Asimov's prose, so often denigrated, is here, as ever, well-wielded in service of his goals. It's not beautiful, but it's well-constructed, and the occasional telling line (as a character's soft sentence about a spaceport wiped out in a Change: "It had been very beautiful") really works. This is the kind of book that made me an SF fan, and it's still worth reading.