The Unbearable Lightness of Being
How we cite our quotes:
It is my feeling that Tomas had long been secretly irritated by the stern, aggressive, solemn "Es muss sein!" and that he harbored a deep desire to follow the spirit of Parmenides and make heavy go to light. Remember that at one point in his life he broke completely with his first wife and his son and that he was relieved when both his parents broke with him. What could be at the bottom of it all but a rash and not quite rational move to reject what proclaimed itself to be his weighty duty, his "Es muss sein!'"? (5.8.5)
This is in line with Tereza's vertigo and Sabina's longing for betrayal. All of these characters in some way harbor a self-destructive impulse that takes its form in self-betrayal.