History, and the progress of time, is thoroughly investigated in both The Unbearable Lightness of Being and We. In both books the authors answer the questions: How is history made? How does time progress? Does it have a direction or does it keep going in circles? If it does have a direction, then what is the trend?
In both novels there are two schools of thought as to how history progresses. One school of thought believes that it continuously follows a certain direction (or at least it should be) while the other belives it keeps on repeating. In The Unbearable Lightness of Being these two categories are defined as "light" and "weight". The reason why a linear history is deemed "light" is because everything happens only once, and according to the saying "Einmal ist Keinmal" (what happens once might not as well have happened at all) this gives them an infinite temporal insignificance, like dust blowing away in the breeze. Likewise eternally recurring history is defined as "weight" as the knowledge that one's actions will be forever repeated will constantly bear down on the actor. The classes of "lightness" and "weight" with respect to history are one of the main features of the novel.
Meanwhile, in We, there are also (more or less) similar schools of thought on history. The One State visions history as a linear progression, which suits the fact that they are the culmination of history very nicely. (There is one exception in Record 20 where D-503 compares the progression of history to circles on an aero. However, the cliff of the One State blocks any further cyclic movement, thus providing an overall negative view to the inifite repetidity of history.) Key to this argument is that revolutions in particular will not repeat indefinitely. The Mephi, of course, believe in the infinity of revolutions. Here I believe the word "revolution" is important, as a revolution is a cycle, a circle. When something turns around once it is considered a revolution. By claiming the infinity of revolutions I-330 and the rest of the Mephi subsequently claim that time itself will continue infinitely along these cycles. I-330 also described history as seasonal (and thus cyclic) when she claimed that some time in the future the Mephi itself must fall "like the autumn leaves from a tree".
What if history wasn't cyclic, however? Here both books also take a more or less similar path. Kundera investigates the process of kitsch, in which beauty and individuality loses its significance and become mundane and banal. Prime examples are the conversion of the castles into barnhouses and the conversion of Sabina's own battle against kitsch into a picture of her surrounded by barbed wire, making her no different from other (again, more or less) anti-Communist protestors. These events are seen as irreversible, as right outside the old church in Amsterdam (kitschified into a hangar) there flows "like a river dividing two empires...an intense smell of urine". "Urine" points to kitsch (as it is created by a bodily process from something possibly beautiful, tasty or artistic into something mundane) and the reference of it to a "river" points to it as having a direction. Equating history to a river means that history, like the river, has a definite direction, and is as much impossible to reverse or return to as a river is to flow back upstream or return to itself. Perhaps the darkest examples of the irreversability of kitsch is what Tomas and Franz are remembered for as they die. Without the ability to understand Tomas and Franz after they were dead their relatives had to resort to kitsch. Tomas became nothing but "He wanted the kingdom of god on earth" while Franz became nothing but "A return after long wanderings". The process of kitsch has reached its conclusion, and Franz and Tomas have been obliterated.
We's hypothesis on a linear history is, in some ways, even darker than The Unbearable Lightness of Being, as in the latter there is always new beauty and individuality created all the time. We equates a linear history to a similar process to kitsch, the process of entropy, whose logical conclusion is not only the obliteration of everything that exists right now, but everything that will ever exist in the future (Zamyatin, however, most likely didn't believe in the process of social entropy, as he didn't believe in the linear progression of history. This is another contrast to Kundera, who acknowledged the process of kitsch to be a truth, which makes kitsch apperar scarier than entropy in some ways.) Entropy is a scientific term which describes the gradual and irreversible slide of the universe towards uniformity. Tending "towards blissful peace, to happy equilibrium", one stressed consequence of absolute entropy is the obliteration of life itself, as "it's in the thermal contrast [the scientific opposite of entropy] that life lies." D-503 himself states that "the ideal (clearly) is a state where nothing actually happens any more."
The contrast between a linear and a cyclic view of history is a rich one and fortunately happens to be deeply explored in both novels with a large number of differences and a small essential number of contrasts, making it quite a good topic to explore further.
