Erichthonius was a mythical king of Athens. He was usually believed to be the son of the gods Hephaestus and Athena, and was often depicted as half man, half serpent. When he became king of Athens, he promoted the worship of his mother. He is often confused with his grandson Erechtheus.
The story of Erichthonius fits into a larger body of myths whose purpose was to justify the political supremacy of Athens in Greece by contending that the early rulers of the city were autochthonous—literally, “from the earth itself.” The idea was to assert that the founders of Athens did not immigrate from other places, and that thus the city did not owe its greatness to other cities, but was a self-made power. Other dynasties traced their families back through generations of humans, but Athenian kings claimed to be direct descendants of the earth, the mother of all living beings.
In most versions of the story, Erichthonius was conceived during an encounter between Athena and Hephaestus. By one account, Athena visited the blacksmith god with an order for some armor, and Hephaestus, who was lonely after having been abandoned by Aphrodite, tried to rape her. In another version, Poseidon harbored a grudge against Athena after she had beaten him in a competition for the patronage of Athens, so encouraged Hephaestus to attack her. Athena fought hard to keep her virginity, using her knee to keep the god at bay, and Hephaestus finally discharged his semen onto her thigh. Athena wiped her leg clean with a piece of wool, which she then threw onto the ground. Divine intercourse is always procreative, and Hephaestus’s seed, wrapped in wool (the product of female labor), on touching the earth, which is also female, caused the conception of the baby Erichthonius. His name refers to the circumstances of his creation: eri - means “wool,” and chthon - means “earth,” thus giving “wool and earth man.”
Poseidon later became the father of Theseus, the greatest Athenian hero, and it may be that the myth of Erichthonius was intended to strengthen the association between Athena and her city’s rulers—Theseus was born to the sixth generation after Erichthonius.