After witnessing many griefs and failures, Cadmus decides to abandon the city of Thebes that he had founded. While he and his wife Harmonia wander the world in exile, Cadmus wonders if the dragon whose teeth he sowed was sacred, and if the gods were angered when he killed it. He wills that he will be turned into a serpent as punishment. Instantly, he transforms into a snake. Before his voice disappears, he begs his wife to embrace him. He wraps himself around Harmonia while she weeps and begs the gods to transform her, too. They grant her wish, and the husband and wife slither into the woods where they live out their days as harmless serpents.
Cadmus’s transformation into a serpent suggests that the dragon he had killed to start his new city was indeed sacred. When he defeated the dragon, Cadmus also defeated nature and wielded his power over it. Years later, his punishment for this abuse of power is to be turned into a snake—into a being without the human power to control nature. Harmonia asks to be transformed as well, showing that, in most cases, people would rather be together in the same form than keep their human form.