The prophecy the Oracle of Delphi made was: that one day a son or grandson would kill King Acricius. This did come true: after Perseus killed Medusa, Polydectes and saved Andromeda he returned to Greece where he searched for King Acricius. He could not find Acricius and Acrucius was no longer king. Perseus and Andromeda lived a happy life in Argo where they had many children (seven sons and two daughters). Perseus took up sports and one day when he was at a track and field competition he threw his discus poorly and it went sailing in the air where a group of spectators were sitting. It hit a man who died because of Perseus' throw. This turned out to Perseus' grandfather; Acricius who was prophesied to die and did, just like the Oracle predicted.
