ay out, Argus, who was all eyes,
sat on a hill close by and kept watch; and you could not say that he
went to sleep at all, for while half of his eyes were shut, the other
half were wide awake, and thus they slept and watched by turns.

Jupiter was grieved when he saw to what a hard life Io had been doomed,
and he tried to think of some plan to set her free. One day he called
sly Mercury, who had wings on his shoes, and bade him go and lead the
cow away from the grove where she was kept. Mercury went down and stood
near the foot of the hill where Argus sat, and began to play sweet tunes
on his flute. This was just what the strange watchman liked to hear; and
so he called to Mercury, and asked him to come up and sit by his side
and play still other tunes.

Mercury did as he wished, and played such strains of sweet music as no
one in all the world has heard from that day to this. And as he played,
queer old Argus lay down upon the grass and listened, and thought that
he had not had so great a treat in all his life. But by and by those
sweet sounds wrapped him in so strange a spell that all his eyes closed
at once, and he fell into a deep sleep.

This was just what Mercury wished. It was not a brave thing to do, and
yet he drew a long, sharp knife from his belt and cut off the head of
poor Argus while he slept. Then he ran down the hill to loose the cow
and lead her to the town.

But Juno had seen him kill her watchman, and she met him on the road.
She cried out to him and told him to let the cow go; and her face was so
full of wrath that, as soon as he saw her, he turned and fled, and left
poor Io to her fate.

Juno was so much grieved when she saw Argus stretched dead in the grass
on the hilltop, that she took his hundred eyes and set them in the tail
of a peacock; and there you may still see them to this day.

Then she found a great gadfly, as big as a bat, and sent it to buzz in
the white cow's ears, and to bite her and sting her so that she could
have no rest all day long. Poor Io ran from place to place to get out of
its way; but it buzzed and buzzed, and stung and stung, till she was
wild with fright and pain, and wished that she were dead. Day after day
she ran, now through the thick woods, now in the long grass that grew on
the treeless plains, and now by the shore of the sea.

[Illustration: "SHE CRIED OUT TO HIM AND TOLD HIM TO LET THE COW GO."]

By and by she came to a narrow neck of the sea, and, since