When Perseus gets challenged by Polydectes to kill the Gorgon Medusa — capable of turning aynone into stone by the mere power of her glance — Hermes and Athena commend him to seek the help of the three Graeae, sisters of the Gorgons.

But the three Graeae, who share only one eye and one tooth among them, won't easily offer their aid.

Perseus steals then their eye and extort the information he needs from them.