In the charming followers of Artemis there was a beautifulfairy maiden called Callisto. Zeus loved her passionately and often sought her company. Before the year was out she bore him a son, Arcas by name. He later became the ancestor of the Archadians. Zeus' frequent absences from Mt Olympus caused Hera's suspicions. In time the vengeful（复仇的） queen discovered the truth and drew up an effective plan of paying back. One day Callisto suddenly found herself changed into a bear, with monstrous（巨大的，怪异的） jaws and bloodshot eyes. Still she remained human in heart. She immediately left her son and went into hiding in the forest.
Years passed. Little Arcas had grown into a young man. He was hunting merrily in the woods one day when a large grey bear suddenly appeared before him. Both were amazed, he terrified at the sight of the frightening bear. The bear recognized that the young hunter was her own son. The young hunter aimed his spear at the slowly approaching bear and was about to pounce（突袭，猛扑） upon it. Just at that moment Zeus stepped in and stopped the foolish act. For he had not been able to find the whereabouts of his lovely mistress until quite recently. He had been secretly protecting her from all danger and harm. Now he turned his son into a little bear, and sent both mother and son into the highheavens. In there they have remained to this day, known as the Great and Little Bear.