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 graze through the day and at night tied a rope round her neck. She would have stretched out her arms to implore freedom of Argus, but that she had no arms to stretch out and her voice was a bellow. She yearned in vain to make herself known to her father. 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. While he thus lamented, Argus, observing, drove her away and took his seat on a bank from whence he could see in every direction. [Illustration: FIG. 47. IO, ARGUS, AND MERCURY] Jupiter, grieved by the sufferings of his mistress, sent Mercury to dispatch Argus. Mercury took his sleep-producing wand and presented himself on earth as a shepherd driving his flock. As he strolled, he blew upon his syrinx or Pandean pipes. Argus listened with delight. "Young man," said he, "come and take a seat by me on this stone. There is no better place for your flock to graze in than hereabouts, and here is a pleasant shade such as shepherds love." Mercury sat down, talked, told stories till it grew late, and played upon his pipes his most soothing strains, hoping to lull the watchful eyes to sleep, but in vain; for Argus still contrived to keep some of his eyes open, though he shut the rest. But among other stories, Mercury told him how the instrument on which he played was invented. "There was a certain nymph," said he, "whose name was Syrinx,--much beloved by the satyrs and spirits of the wood. She would have none of them, but was a faithful worshiper of Diana and followed the chase. Pan, meeting her one day, wooed her with many compliments, likening her to Diana of the silver bow. Without stopping to hear him she ran away. But on the bank of the river he overtook her. She called for help on her friends, the water-nymphs. They heard and consented. Pan threw his arms around what he supposed to be the form of the nymph and found he embraced only a tuft of reeds. As he breathed a sigh, the air sounded through the reeds and produced a plaintive melody. Whereupon the god, charmed with the novelty and with the sweetness of the music, said, 'Thus, then, at least, you shall be mine.' Taking some of the reeds of unequal lengths and placing them together, side by side, he made an instrument and called it Syrinx, in honor of the nymph." Before Mercury had finished his story he saw the eyes of Argus all asleep. At once he slew him and set Io free. The eyes of Argus Juno took and scattered as ornaments on the tail of her peacock, where they remain to this day.