Chthonius was one of the Spartoi (the "Sown Men"), the armed warriors who sprang from the dragon's teeth that Cadmus sowed at the founding of Thebes. After the Sown Men fought and killed one another, only five survived — Echion, Udaeus, Chthonius, Hyperenor, and Pelorus — and these five helped Cadmus build the city and became the ancestors of the Theban nobility. In Greek myth, dragon's teeth, once planted, grew into fully armed men; the motif appears both in the legend of the Phoenician prince Cadmus and in Jason's quest for the Golden Fleece.
Adapted from Wikipedia, "Dragon's teeth (mythology)" · CC BY-SA 4.0
I.Cadmus and the Spartoi
Cadmus, the bringer of literacy and civilization, killed the sacred dragon that guarded the spring of Ares. According to the Bibliotheca, Athena gave Cadmus half of the dragon's teeth, advising him to sow them. When he did, fierce armed men, known as Spartoi ("sown men"), sprang up from the furrows. Cadmus threw a stone among them, because he feared them, and they, thinking the stone had been thrown by one of the others, fought each other until only five of them remained — Echion (future father of Pentheus), Udaeus, Chthonius, Hyperenor, and Pelorus. These five helped Cadmus to found the city of Thebes.
Cadmus was forced to be a slave to Ares for eight years to atone for killing the dragon, after which he was given Harmonia, the daughter of Aphrodite and Ares, to be his wife. Hellanicus, however, writes that only five Spartoi sprang up, omitting the battle between them; in his version Zeus had to intervene to save Cadmus from the anger of Ares, who wished to kill him.
Echion later married Agave, the daughter of Cadmus, and their son Pentheus succeeded Cadmus as king. According to one source, all the descendants of the Spartoi bore a dragon-like mark on their body. King Creon used this mark to recognize his grandson Maeon, who had been raised in secret without his knowledge.
II.The motif of the dragon's teeth
In Greek myth, dragon's teeth feature prominently in the legends of the Phoenician prince Cadmus and in Jason's quest for the Golden Fleece. In each case the dragons are present and breathe fire, and their teeth, once planted, would grow into fully armed warriors.
Similarly to Cadmus, Jason was challenged by King Aeëtes of Colchis to sow dragon's teeth given by Athena in order to obtain the Golden Fleece. Medea, Aeëtes' daughter, advised Jason to throw a stone between the warriors that sprang from the earth. The warriors began fighting and killing each other, leaving no survivor but Jason.
III.Modern references
The phrase "to sow dragon's teeth" is used as a metaphor for fomenting disputes or stirring up conflict that later proves self-destructive.
John Milton alluded to the myth in his prose tract Areopagitica, comparing books to dragon's teeth and describing them as "lively, and vigorously productive" — a defense of the generative power of the written word.