Mnemosyne — Classical Greek Myth Library

On his return with Medusa’s head, Perseus came to Ethiopia, of which Cepheus was king, and found the king’s daughter Andromeda set out as prey for a sea-monster. Cassiepea (Cassiopeia), wife of Cepheus, had vied with the Nereids in beauty and boasted that she surpassed them all. The Nereids took offense; Poseidon, sharing their anger, sent a flood and a monster upon the land. The oracle of Ammon declared that the calamity would end only if Cassiepea’s daughter Andromeda were exposed to the monster. Compelled by the Ethiopians, Cepheus bound his daughter to a rock. Perseus saw her, loved her, and promised Cepheus he would kill the beast if the rescued girl were given him as wife. The oaths sworn, he faced the monster, slew it, and freed Andromeda. Phineus, brother of Cepheus, to whom Andromeda had first been betrothed, plotted against the victor. Perseus discovered the plot and, showing the Gorgon’s head, turned Phineus and his fellow conspirators to stone at once. Apollodorus’s later notice (2.4.5) adds that Andromeda bore Perseus children, among them Perses, whom Perseus left with Cepheus; the Persians were said to take their name from him—a claim Herodotus also records when he treats Persian origins. That genealogical coda belongs to the Ethiopian marriage strand and is noted here rather than as a separate myth.