As with most heroic epics, the destiny of the hero seems to have been spun by the fates before he was even born. This epic tale begins with Aeson, the rightful heir to the throne of Iolcus, and Pelias, his jealous stepbrother. When their father, the King of Iolcus, passed away Pelias imprisoned Aeson and took the crown for himself. However, unknown to Pelias, Aeson's wife bore a son named Jason. Averting JasonŐs certain death at the hand of Pelias, his mother secreted him to the cave of Chiron, a wise and noble centaur. For twenty years Chiron schooled Jason in the arts of the ancient world until the time came for him to claim his birthright.

http://www.theargonauts.com/aboutus/jason_pt01.shtml

Jason and the Argonauts

http://www.pccc.cc.nj.us/asrc/readwrit/jason.html