The three Gorgon sisters—Medusa, Stheno, and Euryale—were all children of the ancient marine deities Phorcys (or "Phorkys") and his sister Ceto (or "Keto"), chthonic monsters from an archaic world. Their genealogy is shared with other sisters, the Graeae, as in Aeschylus's Prometheus Bound, which places both trios of sisters far off "on Kisthene's dreadful plain": Near them their sisters three, the Gorgons, winged With snakes for hair—hatred of mortal man While ancient Greek vase-painters and relief carvers imagined Medusa and her sisters as having monstrous form, sculptors and vase-painters of the fifth century began to envisage her as being beautiful as well as terrifying. In an ode written in 490 BC, Pindar already speaks of "fair-cheeked Medusa". In a late version of the Medusa myth, by the Roman poet Ovid (Metamorphoses 4.794–803), Medusa was originally a beautiful maiden, but when Neptune/Poseidon had sex with her in Minerva/Athena's temple,Minerva punished Medusa by transforming her beautiful hair into horrible snakes And everyone who looks into his eyes will turn to stone