For the love of a woman, a man threatens to destroy the time travel institution he works for, Eternity.

A wonderful story about obsession and time-travel.

Whenever somebody asks about the paradox of time travel, of how changing the past could destroy the person who makes the change, I will from now on have to cite this book. In it, everything is explained. Usually, we talk about parallel universes, so that the person who makes a change in the past is from another universe altogether, so that the change does not affect him. In this book, the Technician, who makes changes, is surrounded by a sort of time stasis field, which protects him. Eternity, the company, exists literally outside of time.

It's amazing to see how much of this book still holds up so well after nearly half a century. The book could have almost been written recently. The only problems are cultural, especially with Asimov's view of women. As always, he sees them as distractions and housewives. But that was how women were viewed in the 1950s, and only Asimov's use of Noys as a special agent makes this book special in that regard. Eternity, however, has no women. The main character starts to envy the maintenance class of people, but how could they be so happy without families?

As usual, we get a very clear picture of the world of Eternity through the actions and thoughts of the main character, Andrew Harlan. There is very little exposition through narration, only from Harlan to himself or Noys or his protégé, Cooper. We get little hints of information, some of it misleading, but all of it is put to good use somewhere, even seemingly-trivial things.

I love the way Harlan is always so passionate in his opinions, and especially how he was always so wrong. His opinions and jealousy of his superior, Computer Finge, was a lot of fun to read about, because it was so over-the-top and so blinding that he just had to be wrong. As a reader, I just had to wait and see how far he would go before realizing that his initial assumptions were wrong, to see how deep he would dig himself, so to speak.

But the really fun part of this book was the time-travel, and how it was so casual. This is another of Asimov's studies of how to make humanity better in spite of itself. It happens also in Robots and Empire, Prelude to Foundation, and again in Foundation and Earth, at least. The people at Eternity deal with altering Time in order to destroy all desperate times, and to make the world a better place. Eternity exists for almost a hundred thousand centuries, and the analysts and psychologists in every century get their input on how to better humanity. In one instance, the destruction of a new technology for spaceflight prevents serious drug addiction for much of humanity centuries "upwhen".

The people in those centuries don't know that a change occurred, of course, as their memories and personalities changed to fit the new Reality. In short, Reality is a fluid thing, and the Eternals take advantage of that.

Humanity also goes through cycles. Through the centuries, humans seem to forget many things, and they repeat social evolution. They create spaceflight many times over the centuries, but abandon it shortly and return to Earth. Ground cars, nuclear power and other technology return again and again. I loved it when Harlan says, on numerous occasions, that such a thing as he was talking about was similar to something in the past or future, and rhymes off several centuries as examples.

Of course, when he is put into a mission that involved the woman, Noys, he falls desperately in love with her, and breaks so many of Eternity's rules in order to keep her unchanged. He plots how she would be altered when her Reality was changed, and brings her into Eternity, hiding her in the Hidden Centuries, years that Eternity has no access to. He comes across a strange plot that he thinks he can use as bribery to keep Noys for himself.

When things start to come together, Harlan doesn't even realize it. Several plots actually unravel at the same time. His superior's casual disregard for the rules is so funny because Harlan doesn't believe it, and he continues to try and sabotage Eternity. His protégé, Cooper, is being sent back to help invent the time stasis field that makes Eternity possible. He manages to disrupt that because he thinks even his most trusted superior is going to kill Noys. Going back in time to try and reverse the damage, he discovers that Noys is actually from the Hidden Centuries, and plans on destroying Eternity herself, through him.

The picture that Asimov paints of humanity's future under the guiding hand of Eternity is a grim one. By eliminating any hardship, Eternity has weeded out the strong people, as well: the ingenious ones. By Noys' time, they have discovered how to look across the infinite alternate realities, and found that humanity died out because they couldn't cope with the mediocrity that total equality brings. Mankind finally did make it out into the Galaxy, but found that they were last to do so, and most primitive, and were seriously inferior to the alien beings that were out there already.

This is a concept that Asimov is well known for believing in, but his first editors would not allow humanity to be even second-best. This is why he created a galaxy with no aliens in it for his Robot, Galactic Empire, and Foundation novels. He did not believe that humanity could be the top galactic species, but more likely somewhere in the middle. That kind of galactic society would have to wait for Devin Brin, and his Uplift series.

So what he does in this novel is to restore humanity to the history that we know, from the early 20th Century, which will allow humans to create a Galactic Empire. I know that there is mention of the Eternals in one of the later-written Foundation novels, and I suppose that rumor could even come from descendants of Harlan and Noys. For although Harlan wants to kill Noys because he discovers who she is, he ultimately decides to give humanity the chance by not rectifying his sabotage. This will strand Cooper in the 20th Century, and not allow him to create the temporal field, which means the End of Eternity.

I liked the sudden turns this book took, and I really loved the setting. I've always loved time travel, and never worried about the loops or paradoxes; in fact, I've always loved the paradoxes, and the means people find ways to explain them. To have an interesting and passionate main character is an added bonus. This was truly enjoyable.