Mnemosyne — Classical Greek Myth Library

Cretheus son of Aeolus founded Iolcus in Thessaly and took Tyro as wife. Tyro had already borne to Poseidon the twins Pelias and Neleus; by Cretheus she bore Aeson, Pheres, and Amythaon. When Cretheus died, the inheritance of Iolcus belonged in right to Aeson, the legitimate son of the founder. Pelias—older, Poseidon-born, and already marked by Hera’s enmity for a slight at her altar—seized the kingship. Neleus went to Messenia and founded or took Pylos; Aeson was thrust aside, kept under watch, or reduced to a private life in the city while Pelias ruled. Fearing the child who might avenge the usurpation, Pelias sought Jason’s death or removal. In the common tale Aeson and Alcimede (or Polymede) sent the boy to Chiron on Pelion to be reared in safety; Pelias received an oracle to beware the one-sandaled man and so lived in dread of any claimant from Aeson’s house. The usurpation is thus the political root of the Argonautica: without Pelias on Aeson’s throne there is no fleece-quest as engineered exile, and no Medea in Corinth. This entry isolates the seizure of Iolcus and Aeson’s displacement from the later riverside recognition (061) and from Medea’s drugs (074, 134).