There was another kingdom in Thessaly near to that of Athamas, and ruled over by a relative of his.  The king Aeson, being tired of the cares of government, surrendered his crown to his brother Pelias on condition that he should hold it only during the minority of Jason, the son of Aeson.  When Jason was grown up and came to demand the crown from his uncle, Pelias pretended to be willing to yield it, but at the same time suggested to the young man the glorious adventure of going in quest of the Golden Fleece, which it was well known was in the kingdom of Colchis, and was, as Pelias pretended, the rightful property of their family.  Jason was pleased with the thought, and forthwith made preparations for the expedition.  At that time the only species of navigation known to the Greeks consisted of small boats or canoes hollowed out from trunks of trees, so that when Jason employed Argus to build him a vessel capable of containing fifty men, it was considered a gigantic undertaking.  It was accomplished, however, and the vessel named “Argo,” from the name of the builder.  Jason sent his invitation to all the adventurous young men of Greece, and soon found himself at the head of a band of bold youths, many of whom afterwards were renowned among the heroes and demigods of Greece.  Hercules, Theseus, Orpheus, and Nestor were among them.  They are called the Argonauts, from the name of their vessel.

The “Argo” with her crew of heroes left the shores of Thessaly and having touched at the Island of Lemnos, thence crossed to Mysia and thence to Thrace.  Here they found the sage Phineus, and from him received instruction as to their future course.  It seems the entrance of the Euxine Sea was impeded by two small rocky islands, which floated on the surface, and in their tossings and heavings occasionally came together, crushing and grinding to atoms any object that might be caught between them.  They were called the Symplegades, or Clashing Islands.  Phineus instructed the Argonauts how to pass this dangerous strait.  When they reached the islands they let go a dove, which took her way between the rocks, and passed in safety, only losing some feathers of her tail.  Jason and his men seized the favorable moment of the rebound, plied their oars with vigor, and passed safe through, though the islands closed behind them, and actually grazed their stern.  They now rowed along the shore till they arrived at the eastern end of the sea, and landed at the kingdom of Colchis.

Jason made known his message to the Colchian king, Aeetes, who consented to give up the golden fleece if Jason would yoke to the plough two fire-breathing bulls with brazen feet, and sow the teeth of the dragon which Cadmus had slain, and from which it was well known that a crop of armed men would spring up, who would turn their weapons against their producer.  Jason accepted the conditions, and a time was set for making the experiment.  Previously, however, he found means to plead his cause to Medea, daughter of the king.  He promised her marriage, and as they stood before the altar of Hecate, called the goddess to witness his oath.  Medea yielded, and by her aid, for she was a potent sorceress, he was furnished with a charm, by which he could encounter safely the breath of the fire-breathing bulls and the weapons of the armed men.