Family of Cadmus:
The founder of Thebes is known as Cadmus or Kadmos. He was a descendant of the union of Io and Zeus in bull shape. Cadmus' father was a Phoenician king named Agenor and his mother was named Telephassa or Telephae. Cadmus had two brothers, one named Thasos, and the other Cilix, who became king of Cilicia. They had a sister named Europa, who was also carried off by a bull -- Zeus, again.
Search for Europa:
Cadmus, Thasos, and their mother went to look for Europa and stopped in Thrace where Cadmus met his future bride Harmonia. Taking Harmonia with them, they then went to the oracle at Delphi for a consultation.
The Delphic Oracle told Cadmus to look for a cow with a lunar sign on either side, to follow where the cow went, and to make sacrifices and establish a town where the bull lay down. Cadmus was also to destroy the guard of Ares.
After finding the cow, Cadmus followed it to Boeotia, a name based on the Greek word for cow. Where it lay down, Cadmus made sacrifices and started to settle. His people needed water, so he sent out scouts, but they failed to return because they had been killed by Ares' dragon who guarded the fountain. It was up to Cadmus to slay the dragon, so with divine assistance, Cadmus slew the dragon using a stone, or perhaps a hunting spear.
Cadmus and the Stones:
Athena, who helped with the slaying, advised Cadmus that he should plant the teeth of the dragon. Cadmus, with or without Athena's help, sowed the teeth-seeds. From them emerged fully armed warriors of Ares who would have turned on Cadmus had Cadmus not thrown stones at them making it appear that they were attacking one another. Ares' men then fought with each other until only 5 worn out warriors survived, who came to be known as Spartoi "the sown men" who then helped Cadmus found Thebes.
Thebes was the name of the settlement. Harmonia was a daughter of Ares and Aphrodite. The conflict between Ares and Cadmus was resolved by the marriage of Cadmus and Ares daughter. The event was attended by all the gods.
Offspring of Cadmus and Harmonia:
Among the children of Harmonia and Cadmus was Semele, who was the mother of Dionysus, and Agave, mother of Pentheus. When Zeus destroyed Semele and inserted the embryonic Dionysus in his thigh, the palace of Harmonia and Cadmus burned. So Cadmus and Harmonia left and traveled to Illyria (which they also founded) first handing over the kingship of Thebes to their son Polydorus, father of Labdacus, father of Laius, father of Oedipus.
Ancient Sources on the House of Thebes:
Apollodorus, Diodorus Siculus, Euripides, Herodotus, Hyginus, Nonnius, Ovid, Pausanias, and Pindar.
Points to Note About the Founding Legend:
- Athena reserved some of the dragon's teeth to give to Jason. See Apollodorus Aeetes.
- Thebes was an Egyptian city, too. One story of the founding of Thebes says that Cadmus gave the Greek city the same name his father had just given to the Egyptian city.
- Instead of Polydorus, Pentheus is sometimes named as the successor of Cadmus.
- Cadmus is credited with bringing the alphabet/writing to Greece.
- The continent of Europe was named for Europa, the sister of Cadmus.
This is the background for the first of three sets of stories from Greek mythology about Thebes. The other two are the sets of stories surrounding the House of Laius, especially Oedipus and those around the conception of Dionysus [see 'The Bacchae' Study Guide].
One of the more enduring figures in the Theban legends is the long-lived, transgendering Tiresius the seer. See: "Ovid's Narcissus (Met. 3.339-510): Echoes of Oedipus," by Ingo Gildenhard and Andrew Zissos; The American Journal of Philology, Vol. 121, No. 1 (Spring, 2000), pp. 129-147/