Juno one day perceived it suddenly grow dark, and immediately suspected that her husband had raised a cloud to hide some of his doings that would not bear the light.  She brushed away the cloud, and saw her husband on the banks of a glassy river, with a beautiful heifer standing near him.  Juno suspected the heifer’s form concealed some fair nymph of mortal mould—­as was, indeed the case; for it was Io, the daughter of the river god Inachus, whom Jupiter had been flirting with, and, when he became aware of the approach of his wife, had changed into that form.

Juno joined her husband, and noticing the heifer praised its beauty, and asked whose it was, and of what herd.  Jupiter, to stop questions, replied that it was a fresh creation from the earth.  Juno asked to have it as a gift.  What could Jupiter do?  He was loath to give his mistress to his wife; yet how refuse so trifling a present as a simple heifer?  He could not, without exciting suspicion; so he consented.  The goddess was not yet relieved of her suspicions; so she delivered the heifer to Argus, to be strictly watched.

Now Argus had a hundred eyes in his head, and never went to sleep with more than two at a time, so that he kept watch of Io constantly.  He suffered her to feed through the day, and at night tied her up with a vile rope round her neck.  She would have stretched out her arms to implore freedom of Argus, but she had no arms to stretch out, and her voice was a bellow that frightened even herself.  She saw her father and her sisters, went near them, and suffered them to pat her back, and heard them admire her beauty.  Her father reached her a tuft of grass, and she licked the outstretched hand.  She longed to make herself known to him, and would have uttered her wish; but, alas! words were wanting.  At length she bethought herself of writing, and inscribed her name—­ it was a short one—­with her hoof on the sand.  Inachus recognized it, and discovering that his daughter, whom he had long sought in vain, was hidden under this disguise, mourned over her, and, embracing her white neck, exclaimed, “Alas! my daughter, it would have been a less grief to have lost you altogether!” While he thus lamented, Argus, observing, came and drove her away, and took his seat on a high bank, from whence he could see all around in every direction.

Jupiter was troubled at beholding the sufferings of his mistress, and calling Mercury told him to go and despatch Argus.  Mercury made haste, put his winged slippers on his feet, and cap on his head, took his sleep-producing wand, and leaped down from the heavenly towers to the earth.  There he laid aside his wings, and kept only his wand, with which he presented himself as a shepherd driving his flock.  As he strolled on he blew upon his pipes.  These were what are called the Syrinx or Pandean pipes.  Argus listened with delight, for he had never seen the instrument before.  “Young man,” said he, “come and take a seat by me on this stone.  There is no better place for your flocks to graze in than hereabouts, and here is a pleasant shade such as shepherds love.”  Mercury sat down, talked, and told stories till it grew late, and played upon his pipes his most soothing strains, hoping to lull the watchful eyes to sleep, but all in vain; for Argus still contrived to keep some of his eyes open though he shut the rest.