Once the stately Juno looked down from high-peaked Olympus and saw Jupiter walking in a meadow with a maiden so exquisitely fair that the flowers at her feet looked dull and faded beside her dazzling whiteness. This was Callisto, so famous for her beauty that suitors came from distant lands to woo her; but she cared nothing for their rich gifts, nor would she listen to any vows of love. Then Jupiter sought her as she wandered alone in the meadow; and the maiden gladly yielded to the great ruler of the gods the love that no mortal man had been able to win. When white-armed Juno learned how many hours Jupiter spent by the side of Callisto, she determined to punish the helpless maiden, and accordingly turned her into a bear. For a long time Jupiter sought her in the familiar meadow, but she never came again to meet him. Then one day he found her in the forest with her little son Arcas--both turned into bears by the jealous hate of Juno. Grieved as he was at this misfortune, the ruler of Olympus could not restore them to their human form; but he took them to the heavens, that they might suffer no further harm, and placed them in the sky as the constellations of the Great and Little Bear.
Jupiter often assumed the form of a bird or animal so as to escape Juno's watchful eyes. As a swan he won the love of Leda, and their child was the fair-haired Helen whose beauty cost the men of Troy so dear. As a white bull he wooed the gentle maid Europa, who was frightened at his sudden appearance in the meadow where she was playing; but as soon as she saw how tame the beautiful animal was and how anxious to be petted, she lost all her fear. She made a wreath of flowers to hang about his neck, and grew so accustomed to her new playmate that she got upon his back as he bent his lordly head to receive her garlands. The bull then galloped away toward the sea, and before the terrified girl could realize what had happened he plunged with her into the waves. As soon as they were far from the land, the white bull spoke gently to Europa and told her who he really was and how, for love of her, he had assumed this strange disguise. So the maiden was no longer afraid, but allowed herself to be carried to an unknown land that was afterward called Europe in her honor.