Medusa part of their religion. Medusa was beheaded by the hero Perseus, who thereafter used her head, which retained its ability to turn onlookers to stone, as a weapon until he gave it to the goddess Athena to place on her shield. In classical antiquity the image of the head of Medusa appeared in the evil-averting device known as the "Gorgoneion". 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
Greek mythology existing literary evidence. Greek mythology has changed over time to accommodate the evolution of their culture, of which mythology, both overtly and in its unspoken assumptions, is an index of the changes. In Greek mythology's surviving literary forms, as found mostly at the end of the progressive changes, it is inherently political, as Gilbert Cuthbertson has argued. The earlier inhabitants of the Balkan Peninsula were an agricultural people who, using Animism, assigned a spirit to every aspect of nature. Eventually, these vague spirits assumed human forms and entered the local mythology as gods. When tribes from the north of the