When the Argo with its triumphant crew reached Thessaly, they found that their arrival caused great surprise as well as joy, for King Pelias had never supposed they would return, and felt himself secure against any further trouble from the youth with only one sandal. He was therefore much dismayed at seeing Jason return, especially as he came unharmed and bearing so rich a trophy as the golden fleece. The usurper knew that his days of power were over, and when Jason again demanded the kingdom in his father's name, Pelias was forced to resign his throne to the lawful king. Old Æson was then summoned from his place of banishment, and restored to his rightful place; but he was so weak and decrepit that power had no charm for him, and he accepted his throne very reluctantly.
So Jason begged his wife to use her magic in behalf of the old king; and Medea, anxious to please her lover, willingly promised to restore Æson to all the vigor of manhood. To prepare the magic potion that was to bring youth and health, the sorceress went out into the meadows on nine successive nights beginning with the new moon, and gathered herbs whose magic properties she alone could tell. Then she set a caldron in the deepest part of the woods, and built under it a slow fire that burned always night and day. In the caldron she threw the magic herbs, flowers with acrid juice, stones from the far east and sand from the all-surrounding ocean, hoar frost gathered by moonlight, a screech-owl's head and wings, and the entrails of a wolf. Then she added some bits of tortoise shell and the liver of a stag--for these animals are tenacious of life--and the head and beak of a crow that outlives nine generations of men. All these she boiled together,[96] stirring them with an olive branch; and when she lifted out the branch, it was full of new leaves and heavy with young olives. These preparations being finished, and the time being full moon, Medea went forth alone into the forest with old Æson, just at midnight when all creatures slept, and no breath of wind stirred the trees. She laid the old man on a bed of herbs, and after putting him into a deep sleep, cut his throat and let out the sluggish blood of age. Then she poured into the wound the juices from her caldron; and when these began to flow through the king's weak frame, he underwent a wonderful change, for his hair and beard lost their whiteness and took on the glossy hue of youth. His paleness changed to the ruddiness of manhood; and his feeble limbs felt all the vigor of a hero in his prime.