Perilous as this task seemed, each of the heroes was eager to undertake it, but Jason, as the leader of the expedition, took it upon himself. Fortune favored him in the desperate undertaking. Medea, the daughter of AEetes, who knew all the arts of magic, had seen the handsome youth and fallen in love with him at sight. She now came to his aid with all her magic. Gathering an herb which had grown where the blood of Prometheus had fallen, she prepared from it a magical ointment which, when rubbed on Jason's body, made him invulnerable either to fire or weapons of war. Thus prepared, he fearlessly approached the fire-breathing bulls, yoked them unharmed, and ploughed the field, in whose furrows he then sowed the dragons' teeth. Instantly from the latter sprang up a crop of armed men, who turned their weapons against the hero. But Jason, who had been further instructed by Medea, flung a great stone in their midst, upon which they began to fight each other, and he easily subdued them all. Jason had accomplished his task, but AEetes proved unfaithful to his words. He not only withheld the prize, but took steps to kill the Argonauts and burn their vessel. They were invited to a banquet, and armed men were prepared to murder them during the night after the feast. Fortunately, sleep overcame the treacherous king, and the adventurers warned of their danger, made ready to fly. But not without the golden fleece. This was guarded by a dragon, but Medea prepared a potion that put this perilous sentinel to sleep, seized the fleece, and accompanied Jason in his flight, taking with her on the Argo Absyrtus, her youthful brother. The Argonauts, seizing their oars, rowed with all haste from the dreaded locality. AEetes, on awakening, learned with fury of the loss of the fleece and his children, hastily collected an armed force, and pursued with such energy that the flying vessel was soon nearly overtaken. The safety of the adventurers was again due to Medea, who secured it by a terrible stratagem. This was, to kill her young brother, cut his body to pieces, and fling the bleeding fragments into the sea. AEetes, on reaching the scene of this tragedy, recognized these as the remains of his murdered son, and sorrowfully stopped to collect them for interment. While he was thus engaged the Argonauts escaped. But such a wicked deed was not suffered to go unpunished. Jupiter beheld it with deep indignation, and in requital condemned the Argonauts to a long and perilous voyage, full of hardship and adventure. They were forced to sail over all the watery world of waters, so far as then known. Up the river Phasis they rowed until it entered the ocean which flows round the earth. This vast sea or stream was then followed to the source of the Nile, down which great river they made their way into the land of Egypt.