"You must earn the fleece, Jason," he said. "Nothing so valuable can be had for only the asking. Are you brave enough to yoke my bulls to a plough and plant a field full of dragon's teeth?" Jason gasped. He knew these bulls of Colchis by reputation, although it had never occurred to him that he might be called upon to harness and drive them. They had brazen teeth and breathed fire from their nostrils that consumed whatever it touched. The sound of their breathing was like the roar of a furnace, and the smoke of their breath was suffocating. In spite of his fear, though, Jason had another thought. The king had said that the fleece must be earned, that nothing so golden could be had for the asking. That was really true, Jason thought, and he began to feel a great courage. He was growing into the hero that he always had been at heart, being a youth of Greece. "Send out your bulls," he said to the king of Colchis. Something happened then that is very apt to happen when anyone makes up his mind to dare a seemingly impossible deed. Help came to Jason. Medea, the daughter of the king of Colchis, gave Jason a charm that protected him from fire. The bulls rushed into the field toward Jason, sending forth their burning breath like dragons, but Jason advanced boldly to meet them. His friends, the Argonauts, watched him in terror, but he went straight up to the bulls and his voice seemed to soothe their rage. He stroked their necks fearlessly, slipped on the yoke and harnessed them to the plough. Dragons' teeth were a strange kind of seed to plant. As Jason ploughed straight furrows and dropped in the teeth, the people of the kingdom and the Argonauts gathered at the edge of the field to watch, and it came to his mind that perhaps the king was making a joke of him. There would have been some sense in having that pair of fiery bulls use their great strength to plough in corn and wheat, Jason thought, as he plodded up and down the field. But suddenly a cry from the crowd startled Jason and he looked back. A strange sight met his eyes. The clods of earth that covered the teeth of the dragon began to stir, and the bright points of spears thrust their way up through to the surface. Helmets with nodding plumes appeared next, and after them came the shoulders and arms and limbs of men. In a moment the field was alive with armed warriors advancing upon Jason. He was only one hero against all of this foe, but the sight put the same courage that had come to him into the heart of each one of the Argonauts and they rushed to help their leader. Jason led valiantly against the warriors, but there would have been no hope for him and the Greeks if his courage had not been rewarded a second time. Medea sent a charmed sword to the hero. He threw it into the ranks of the warriors and they suddenly ceased attacking the Greeks, fell to fighting among themselves, and were destroyed.