The narrator claims that he will not try to convince the reader that Tomas and Tereza actually lived. He has created them, and Tereza was born the first day she visited Tomas’s flat with a rumbling stomach. “When we ignore the body,” the narrator says, “we are more easily victimized by it.”
Tereza represents the soul, and she hates her body, especially bodily functions, such as the rumbling of the stomach. Tereza wants to forget about her body, banish it in a sense, and be only a soul, but her noisy stomach is a painful—and humiliating—reminder of her body.