Cad`mus, a semi-mythological personage, founder of Thebes, in Boeotia, to whom is ascribed the introduction of the Greek alphabet from Phoenicia and the invention of writing; in the quest of his sister Europa, was told by the oracle at Delphi to follow a cow and build a city where she lay down; arrived at the spot where the cow lay down, he sent, with a view to its sacrifice, his companions to a well guarded by a dragon, which devoured them; slew the dragon; sowed its teeth, which sprang up into a body of armed men, who speared each other to death, all but five, who, the story goes, became the forefathers of Thebes.