" (Kundera: 60) at this point, a strong connection between body and soul is forged. Her mother is unwell, and Tereza wants to visit her. However, Tomas opposes this trip so she does not go. Tereza falls in the street hours later and injures herself. What follows is a series of small accidents which are symbols of her soul falling as well: "She was in the grip of an insuperable longing to fall. She lived in a constant state of vertigo." (Kundera: 61) the third step in the evolution of her dualism occurs when Tereza embarks on an extramarital affair with an engineer. She wants to become like Tomas hoping she can get back at him and his infidelities. The intimate relationship established between the two helps Tereza understand both her body and her soul. The touch of his hand on her breast "erased what remained of her anxiety. For the engineer's hand referred to her body, and she realized that she was not at all involved, only her body, her body alone." (Kundera: 154) She also learns that she cannot resist the touch of the engineer although at first she does not respond to it. Although her soul does not take part in the affair, her body is filled with excitement and responds very much against Tereza's will. However, she realizes that in order for her body to remain responsive, her soul must be silenced: "The moment it said its yes aloud, the moment it tried to take an active part in the love scene, the excitement would subside. For what made the soul so excited was that the body was acting against its will; the body was betraying it, and the soul was looking on." (Kundera: 155). The fact that her soul is a silent actor allows Tereza to see her own body in a different light for the first time; she is now fascinated with it, and regards it as something extraordinary: "This was not the most ordinary of bodies (as the soul had regarded it until then); this was the most extraordinary body." (Kundera: 155) the affair makes her realize that once the engineer is no longer looking at her, her excitement turns to "an intoxicating hatred" and she is "overcome by a feeling of infinite grief and loneliness." (Kundera: 157). These feelings of grief and loneliness determine the soul to retreat to the depths of her physical being "waiting desperately for someone to call it out." (Ibid) Tereza ultimately realizes that the affair with the engineer is weightless, and that the sight of her soul could only be restored through it: "But her soul was still blinded by love, and saw nothing. Making love with the engineer in the absence of love was what finally restored her soul's sight." (Kundera: 161) Tomas is a Czech intellectual who is politically silenced by the oppressive regime because he refuses to side with the Communists. He loses the right to practice medicine and is first a window washer, and then a farmer. This change in his life brings about alienation as he feels he no longer matter to anyone. Although he is presented as a seducer who can have any woman he wants, Tomas spends his life avoiding excitement and romance; his life is well-ordered and under his complete control: "Missions are stupid, Tereza. I have no mission. No one has. And it's a terrific relief to realize you're free, free of all missions" (Kundera: 313). Moreover, he disregards the laws of politics and love which he finds trivial and labels as kitsch. Tomas's duality is very clearly defined as the dichotomy between love and sex dictates that between soul and body. He is in love with his wife but sleep with other women. From this perspective, Tomas does not consider this aspect as problematic. Instead, he believes that love and casual sex are unrelated hence his soul can belong to one woman whereas his body is free to experiment.
His philosophy of lightness dictates that love and sexual encounters are unrelated; this way he leads a sexually experimental existence even though he is married to Tereza: "Tomas kept trying to convince her that love and love-making were two different things. She refused to understand." (Kundera: 142). The opposite of a romantic idealist, Tomas is deeply pragmatic and experienced, displaying individualism at its purest form: "Human decisions are terribly simple." (Kundera: 308). Hence he is unwilling to give up his freedom and identify himself as a liberal or a faithful husband; instead, he maintains his freedom and individuality and consequently, his "lightness": "He was not at all sure he was doing the right thing. But he was sure he was doing what he wanted to do" (Kundera: 220).
Tomas is a character that changes considerably throughout the novel; he grows as a result of his experiences. Tomas first feels the heaviness of being when Tereza goes back to Czechoslovakia and he remains in Zurich. His initial feeling is one of lightness because he is now free to fully experience life. "She might as well have chained an iron ball to his ankles. Suddenly his step was much lighter. He soared. He had entered Parmenides' magic field: he was enjoying the sweet lightness of being." (Kundera: 30). However, shortly after her departure, Tomas begins to miss her: "On Saturday and Sunday, he felt the sweet lightness of being rise up to him out of the depths of the future. On Monday, he was hit by a weight the likes of which he had never known. The tons of steel of the Russian tanks were nothing compared to it. For there is nothing heavier than compassion." (Kundera: 31) Tomas tries to resist the heaviness i.e. The feeling of compassion and loss, but is unsuccessful. Towards the end, when he abandons his job and moves to the country with Tereza, he realizes that the soul and the body are indeed separate entities, but that they cannot live in isolation from one another.
Sabina is Tomas's favorite lover, an artist who rebels against the ugliness of the surrounding world, and her oppressive father through her paintings and lifestyle choices. She is the extreme instance of the lightness of being. In fact, her love affair with Tomas is based upon this very lightness of being that they share. Their affair has nothing in common with a traditional romance as they are not traditional characters. Nevertheless, she looks for heaviness, which is why she falls in love with Franz, a university professor and at the same time, the extreme instance of heaviness: "Her drama was a drama not of heaviness but of lightness. What fell to her lot was not the burden but the unbearable lightness of being." (Kundera: 122). Also, upon meeting Tereza, she is fascinated with her. Sabina is absolutely free and deeply individualistic; she abandons Franz without any notice or explanation and moves to America where she wonders whether or not she has anything left to leave or betray: "She sensed an expanse of freedom before her, and the boundlessness of it excited her. She made mad, unrestrained love to Franz as she never had before." (Kundera: 116). She is aware that her choices might leave her lonely and empty which makes her uneasy, but just like Kundera, she never returns to her homeland. Sabina commits her entire life to lightness. Upon learning of the deaths of Tereza and Tomas, she decides that she wants to be cremated after she dies, and her ashes scattered to the winds: "Tereza and Tomas had died under the sign of weight. She wanted to die under the sign of lightness. She would be lighter than air. As Parmenides would put it, the negative would change to positive." (Kundera: 273) Franz is a university professor who teaches philosophy and falls in love with Sabina, his exact opposite. Franz is a heavy character who looks for meaning in life and lives for strong emotions generated either by love or by politics. He is a combination of idealism, naivete and the inability to understand his surroundings. Franz is also married. The heaviness of his being keeps him from consummating his adulterous relationship in Geneva because "he felt, (it) would humiliate both mistress and wife and, in the end, himself as well." (Kundera: 81) However, this is not necessarily a decision dictated by morality or social convention: "The ban on making love with his painter-mistress in Geneva was actually a self-inflicted punishment for having married another woman. He felt it as a kind of guilt or defect." (Kundera: 83). Franz is the epitome of commitment and functions according to a very strict set of rules that he imposes on himself. In this sense, he does not acknowledge the dichotomy between body and soul as he perceives the two as being inextricably linked and dependent upon one another.