The Medusa once had been a beautiful woman with long and glowing hair. So proud was she of her beauty that she dared compare herself with Athena, the Goddess of War. On hearing of the woman's bragging, Athena turned Medusa into a hideous monster. Where her long beautiful hair had once hung were now writhing and hissing snakes. So hideous was the sight of her that any human or animal who chanced a gaze upon her was instantly turned to stone. Perseus was a favorite of Athena and the wing-footed god, Hermes. Athena lent Perseus her bright shield and Hermes lent him his winged shoes. So equipped, Perseus set out and flew over sea and land to where the Medusa lived. The Medusa was sleeping when Perseus arrived. Silently he crept toward her, while not looking at her directly. So bright was Athena's shield that he could clearly see the Medusa's reflection in it and so he backed toward her and with a mighty back-handed blow cut off her head. Then with his eyes closed he seized it and stuffed it into the special sack he had brought along. It was when Perseus was flow over the coast of Æthiopia (not present day Ethiopia) that he noticed Andromeda chained to the rocks by the sea, and not far away he could see Cetus, the sea-monster as a whale, rapidly nearing her. Down he swept to the girl's side. "Why are you thus bound?" he asked, overwhelmed by Andromeda's beauty. Andromeda told him the story of her boastful mother and the advice the oracle had given her father. Perseus quickly turned to Cepheus, King of Æthiopia and said: "I can save your daughter from the sea-monster, but for my reward I demand Andromeda's hand in marriage, and a kingdom." Cepheus promised Perseus that he would have what he asked for, whereupon Perseus unsheathed his sword and leapt into the air to the attack. One thrust of his sword found a soft spot between the armored scales of the monster. Wounded, it twisted over on its side. Perseus then inflicted another deep cut, and another. Blood now colored the water red and soaked Perseus' winged shoes. Fearful of losing his ability to fly, he settled on a rock near the shore and waited for the sea-monster to attack again. As it did, Perseus' sword plunged deeply into the monster's evil heart. Joyful beyond words, Cepheus and Cassiopeia led Perseus and Andromeda to their house, where a great feast and celebration were prepared. Perseus and Andromeda were married and led a long, happy life together. There first-born son, Peres, is said to have given rise to those people who became known as Persians. Later in life, Perseus was throwing the discus in an athletic contest when a stray throw struck and killed a spectator. The unfortunate spectator was Perseus grandfather, and the prophecy that he would be killed by his grandson was fulfilled. When Perseus and Andromeda died, they were given honored places among the stars by the goddess Athena. Cetus, the sea-monster, was there waiting for them and forever chases Andromeda around the sky, but Perseus continues to guard her well. Meanwhile Cepheus and Cassiopeia had died and were likewise given honored places among the stars by Poseidon. Poseidon saw to it that his beloved Medusa also was given a place among the stars. To this day she can be seen as the star Algor, which is the second brightest star forming Perseus and is located near his waist and beneath his upraised right arm.
Perseus was the son of Zeus and the mortal Danaë. Danaë's father was told by an oracle that his grandson would kill him one day, so he set Danaë and Perseus adrift in a trunk. They were rescued by a fisherman and went to live on his island. The king of the island wished to date Danaë and sent Perseus away to kill the Medusa.