 However, Herodorus says that Heracles did not sail at all at that time but served as a slave at the court of Omphale.But Pherecydes says that he was left behind at Aphetae in Thessaly, the Argo having declared with human voice that she could not bear his weight.Nevertheless Demaratus has recorded that Heracles sailed to Colchis; for Dionysius even affirms that he was the leader of the Argonauts.