Why should you toil in the midday heat? You need not be afraid to enter the dim forest where beasts crouch in the dusky ravines, for am I not here to protect you, I, who weigh in my hand the scepter of the sky and flash jagged lightning over the earth?”

But the girl sped from her tempter, and fear winged her feet, so that she would surely have escaped him, had he not abused his power and plunged the entire region into darkness. She was muffled in mists and slowed her steps in alarm lest she stumble against a rock or lose her footing and slip into a river. And so unhappy Io fell into the snares of Zeus.

Hera, the mother of the gods, had long since grown accustomed to her husband’s faithlessness, for he frequently turned from her to lavish love on the daughters of demigods and mortals. Yet she had never learned to curb her anger and jealousy, but watched every move of Zeus on earth with unflagging distrust. Now too her gaze rested upon that very region where her husband was disporting himself without her knowledge, and she saw with amazement that in one particular spot the clear day was blurred with heavy mists which rose neither from the river nor the ground, nor were they due to any other natural cause. Her suspicions were instantly aroused. She looked for Zeus over all Olympus, but he was not there. “If I am not mistaken,” she said sullenly to herself, “my husband is doing me a grave wrong.”

And forthwith she left the high air of heaven, floated down to earth in a cloud, and bade the mists which walled in the seducer and his quarry break apart. Zeus had divined her coming, and to save his beloved from her vengeance, he changed the lovely daughter of Inachus into a snow-white heifer. Even so, the girl was still fair to look upon. Hera, seeing at once through her husband’s ruse, praised the stately animal and guilefully asked to whom it belonged, what breed it was, and where it had come from. In his embarrassment and desire to put an end to her questions, Zeus lyingly told her that the heifer was a mere creature of earth and nothing more. Hera pretended to be satisfied with his answer, but begged him to make her a present of the fine beast. What was the cheated cheat to do? If he granted her request he would lose his beloved; if he refused, her smoldering suspicions would burst into flame and she would surely destroy the unfortunate girl. For the time being, then, he decided to do without her and gave his wife the shimmering creature, whose secret he thought well-hidden.

Hera seemed charmed with the gift. She knotted a ribbon about the neck of the beautiful heifer, whose heart beat under the animal pelt in mortal despair, and led her off in triumph. But the goddess herself had misgivings about her action and knew she would not be at ease until she had given her rival into very safe keeping. She went in search of Argus, the son of Arestor, who seemed well suited for the task she had in mind. For Argus was a monster with a hundred eyes, of which he closed only one pair at a time, while the rest, glittering like stars over the front and back of his head, remained open and faithful to their duties. It was to Argus that Hera entrusted Io, so that Zeus would be unable to regain the mistress she had deprived him of. Fixed by those hundred eyes, the heifer was allowed to graze on slopes, green with luxuriant grass, the livelong day, but wherever she went, never was she out of sight of Argus, even when she moved behind him. At nightfall he locked her up and weighed her neck with heavy chains. She dined on bitter herbs and leathery leaves, lay on the hard bare ground, and drank from turbid pools. Often Io forgot that she was no longer human. She wanted to lift her hands in supplication, only to remember that she had no hands. She wanted to plead with Argus in sweet, compelling words, but when she opened her mouth she shrank from the lows she uttered. Argus did not keep her in one place, for Hera had bidden him pasture her far and wide, so that it would be difficult for Zeus to discover her. Thus it was that she and her guard roamed the countryside, until one day she found herself in her native land, on the bank of the river where she had so often played as a child. Now for the first time she saw herself in her altered shape, and when the head of a horned beast stared back at her from the bright mirror of the waters, she fled from her own image in shuddering alarm. Driven by longing, she turned toward her sisters and her father, but they did not recognize her.