Lightness and Weight, history

And again he thought the thought we already know: Human life occurs only once, and the reason we cannot determine which of our decisions are good and which bad is that in a given situation we can make only one decision; we are not granted a second, third, or fourth life in whic to compare various decisions...
If Czech history could be repeated, we should of course find it desirable to test the other possibility each time and compare the results. Without such an experiment, all considerations of this kind remain a game of hypotheses.
Einmal ist keinmal. What happens but once might as well not have happened at all. The history of the Czechs will not be repeated, nor will the history of Europe. The history of the Czechs and of Europe is a pair of sketches from the pen of mankind's fateful inexperience. History is as light as individual human life, unbearably light, light as a feather, as dust swirling into the air, as whatever will no longer exist tomorrow.