The Unbearable Lightness of Being explores the miscommunication that passes between a man and a woman in a relationship together. Kundera uses the metaphor of musical compositions with repeated motifs to describe an individual's life and the recurring concepts in it. If two people meet too late in life, he says, their musical compositions are already written. They cannot exchange motifs and will forever misunderstand the recurring ideas in each other's life. In one brilliant section of the novel, Kundera presents a "Dictionary of Misunderstood Words" that pass between two lovers – Franz and Sabina – who define everything from "betrayal" to "woman" in opposite terms.
The only pure, effective communication in this novel is that which is unspoken. Language necessarily corrupts communication.
Tereza and Tomas's communication is perfect and stands in opposition to that of Franz and Sabina.