Tomas feels “utterly powerless” after Tereza leaves, but he finds this feeling strangely comforting. He is not being forced by anyone to either stay in Zurich or follow Tereza back to Prague, and she had not been forced to return to Czechoslovakia. Tereza has left his life the same way she entered it: with an enormous suitcase. Without Tereza, Tomas feels less heavy, and, as Parmenides’s theory stipulates, Tomas is “enjoying the sweet lightness of being,” but he doesn’t want to call any of his mistresses. Tomas knows that the memory of Tereza will make being with another woman too painful to bear.
Technically, Tomas is light, because he has lost Tereza and her heavy emotions and baggage, but he still isn’t entirely without weight. He can’t enjoy himself and see one of his mistresses—the height of his “light” behavior—because he is too bogged down by his love for Tereza. He isn’t light, he is heavy, and Tereza holds all the power by leaving him in such a state, even though no one is forcing him to act in any certain way.