Mnemosyne — Classical Greek Myth Library

Io, daughter of the Argive river-god Inachus (or, in variant genealogies, of Iasus or Peiren), was priestess of Hera at Argos. Zeus loved her. To hide the affair from Hera, he transformed Io into a white cow—or Hera herself effected the change after discovering them. Hera demanded the cow as a gift and set Argus Panoptes, the many-eyed watchman, to guard her. Zeus sent Hermes to free Io. Hermes lulled Argus with song and stories (or with the newly invented syrinx) and killed him; from that deed Hermes gained the epithet Argeiphontes (“Argus-slayer”). Hera set Argus’s eyes in the peacock’s tail and sent a gadfly to torment the cow-Io. Driven across the Ionian Sea (named from her, in folk etymology), through the Bosporus (“cow-ford”), Scythia, and the Caucasus, Io wandered until she reached Egypt. There Zeus restored her human form by a touch (hence Epaphus, “Touch”). She bore Epaphus, who became a king in Egypt; from his line descended Libya, Agenor, Belus, and eventually Danaüs and the Danaids who returned to Argos—the genealogical bridge between Argive and Egyptian myth in tragedy and handbook tradition. Aeschylus’s *Prometheus Bound* stages Io’s meeting with the bound Prometheus, who prophesies her wanderings and destiny.