“Foot-feather’d Mercury appear’d sublime
Beyond the tall tree tops; and in less time
Than shoots the slanted hail-storm, down he dropt
Towards the ground; but rested not, nor stopt
One moment from his home; only the sward
He with his wand light touch’d, and heavenward
Swifter than sight was gone.”
Keats.
Mercury was not only the messenger of the gods, but was also appointed god of eloquence, commerce, rain, wind, and the special patron of travelers, shepherds, cheats, and thieves.
Story of Io.
Jupiter often intrusted to Mercury messages of a delicate nature, and always found him an invaluable ally; but the faithful messenger was never so much needed or so deeply appreciated as during Jupiter’s courtship of Io, the peerless daughter of the river god Inachus.
To avoid Juno’s recriminations, Jupiter had carried on this affair with even more than his usual secrecy, visiting his beloved only when quite certain that his wife was asleep, and taking the further precaution of spreading a cloud over the spot where he generally met her, to shield her from all chance of being seen from Olympus.
One fine afternoon, all conditions being favorable, Jupiter hastened down to earth to see Io, and began to stroll with her up and down the river edge. They heeded not the noonday heat, for the cloud over their heads screened them from the sun’s too ardent rays.
From some cause Juno’s slumbers were less protracted than usual, and she soon arose from her couch to look about her realm, the atmosphere, and convince herself that all was well. Her attention was soon attracted by an opaque, immovable cloud near the earth,—a cloud which had no business there, for had she not bidden them all lie still on the blue until she awoke? Her suspicions being aroused by the presence of this cloud, she sought her husband in Olympus, and, not finding him, flew down to earth, brushing the cloud aside in her haste.
Jupiter, thus warned of her coming, had but time to change the maiden beside him into a heifer, ere his wife alighted and inquired what he was doing there. Carelessly the god pointed to the heifer, and declared he had been whiling away the time by creating it; but the explanation failed to satisfy Juno, who, seeing no other living creature near, suspected that her spouse had been engaged in a clandestine flirtation, and had screened its fair object from her wrath only by a sudden transformation.
Dissimulating these suspicions with care, Juno begged her husband to give her his new creation, which request he could not refuse, but granted most reluctantly, thus adding further confirmation to her jealous fears. The Queen of Heaven then departed, taking Io with her, and placed her under the surveillance of Argus, one of her servants, who possessed myriad eyes, but one half of which he closed at a time.
“The eyes of Argus, sentinel of Heaven:
Those thousand eyes that watch alternate kept,
Nor all o’er all his body waked or slept.”
Statius (Elton’s tr.).