the herdsman of Io."Hesiod or Cercops of Miletus, Aegimius Frag 5 :"And set a watcher upon her , great and strong Argos, who with four eyes looks every way. And the goddess stirred in him unwearying strength: sleep never fell upon his eyes; but he kept sure watch always."
Aeschylus, Prometheus Bound 566 ff (trans. Weir Smyth) (Greek tragedy C5th B.C.) :"Io : Oh, oh! Aah! Aah! A gad-fly (oistros), phantom (eidôlon) of earth-born (gêgenês) Argos is stinging me again! Keep him away, O Earth! I am fearful when I behold that myriad-eyed herdsman. He travels onward with his crafty gaze upon me; not even in death does the earth conceal him, but passing from the shades he hounds me, the forlorn one, and drives me famished along the sands of the seashore.The waxen pipe drones forth in accompaniment a clear-sounding slumberous strain. Alas, alas! Where is my far-roaming wandering course taking me? . . . I cannot discern how to escape my sufferings."
Aeschylus, Prometheus Bound 669 ff :" Yielding obedience to such prophetic utterances of Loxias , he drove me away and barred me from his house, against his will and mine; but the constraint of Zeus forced him to act by necessity. Immediately my form and mind were distorted, and with horns, as you see, upon my forehead, stung by a sharp-fanged gadfly I rushed with frantic bounds to Kerkhnea"s sweet stream and Lerna"s spring. But Argos, the earth-born (gêgenês) herdsman, untempered in his rage, pursued me , peering with his many eyes upon my steps. A sudden death robbed him of life unexpectedly; while I, still tormented by the gadfly, am driven on from land to land before the heaven-sent plague."
Aeschylus, Suppliant Women 292 ff :"Chorus : Is there a report that once in this land of Argos Io was ward of Hera"s house?King : Certainly she was; the tradition prevails far and wide.Chorus : And is there some story, too, that Zeus was joined in love with a mortal?King : This entanglement was not secret from Hera.Chorus : What then was the result of this royal strife?King : The goddess of Argos transformed the woman into a cow.Chorus : And while she was a horned cow, did not Zeus approach her?King : So they say, making his form that of a bull lusting for a mate.Chorus : What answer then did Zeus" stubborn consort give?King : She placed the all-seeing one (panoptês) to stand watch over the cow.Chorus : What manner of all-seeing herdsman with a single duty do you mean?King : Argos, a son of Ge (Gaea, Earth), whom Hermes slew."

Zeus, Hera, Io as heifer, Argus Panoptes and Hermes, Athenian red-figure hydria C5th B.C., Museum of Fine Arts BostonPseudo-Apollodorus, Bibliotheca 2. 4 ff (trans. Aldrich) (Greek mythographer C2nd A.D.) : "The son of Ekbasos (Ecbasus) was Agenor, and his son was Argos surnamed Panoptes. This man had eyes all over his body. He was extremely powerful, and killed the bull that raged through Arkadia (Arcadia) whose hide he used as a cloak. He also ambushed and slew and Satyros who was hurting the Arkadians by stealing their herds. It is also said that he waited until Ekhidna (Echidna) fell asleep, and then killed her. She was a daughter of Tartaros and Ge (Gaea, Earth), who would kidnap travellers passing by. Argos also avenged the murder of Apis by slaying the guilty pair, Thelxion and Telkhis (Telchis) . . .Zeus seduced Io while she was a priestess of Hera. When Hera discovered them, Zeus touched the girl, changed her into a white cow, and swore that he hand not had sex with her . . .Hera demanded the cow from Zeus, and assigned Argos Panoptes as its guard. Pherekydes (Pherecydes) says that this one was Arestor"s son, but Asklepiades (Asclepiades) says he was a descendant of Inakhos (Inachus). Kerkops (Cercops) calls him a son of Argos and Asopos" daughter Ismene , while Akousilaos (Acusilaus) says he was Earth-Born. Argos tied the cow to an olive tree in the grove of the Mykenaians (Myceneans). Zeus instructed Hermes to steal her, and Hermes, unable to sneak her out because Hierax had told on him, killed Argos with a stone. From this came Hermes" surname Argeiphontes."
Quintus Smyrnaeus, Fall of Troy 10. 190 ff (trans. Way) (Greek epic C4th A.D.) :" There Hermes was, storm-footed Son of Zeus, laying huge Argos nigh to Inakhos" (Inachus") streams, Argos, whose sentinel eyes in turn took sleep."
Pausanias, Description of Greece 2. 16. 4 (trans. Jones) (Greek travelogue C2nd A.D.) :"The fair-crowned lady Mykene (Mycene). She is said to have been the daughter of Inakhos (Inachus) and the wife of Arestor in the poem which the Greeks call the Great Eoeae."
Pseudo-Hyginus, Fabulae 145 (trans. Grant) (Roman mythographer C2nd A.D.) :"From Inachus and Argia Io. Jupiter loved and embraced Io, and changed her to heifer form so that Juno would not recognize her. When Juno found out, she sent Argus, who had gleaming eyes all around to guard her. Mercurius , at Jove"s command, killed him."
Ovid, Metamorphoses 1. 624 ff (trans. Melville) (Roman epic C1st B.C. to C1st A.D.) :"Juppiter had fore-sensed his spouse"s visit and transformed poor Inachis into a sleek white heifer (lovely still although a cow). Saturnia , against her will, admired the creature and asked whose she was, and whence she came and to what herd belonged, pretending not to know the truth. He lied--‘The earth had brought her forth’--so to deflect questions about her birth. Then Saturnia begged the heifer as a gift. What should he do? Too cruel to give his darling! Not to give--suspicious; shame persuades but love dissuades. Love would have won; but then--if he refused his wife (his sister too) so slight a gift, a cow, it well might seem no cow at all!The goddess won her rival, but distrust lingered and still she feared her husband"s tricks, till, for safe-keeping, she had given the cow to Arestorides (Son of Arestor)--Argus of the hundred eyes, all watching and on duty round his head, save two which took in turn their sleep and rest. Whichever way he stood he looked at Io, Io before his eyes behind his back! By day he let her graze, but when the sun sank down beneath the earth he stabled her and tied--for shame!--a halter round her neck. She browsed on leaves of trees and bitter weeds, and for her bed, poor thing, lay on the ground, not always grassy, and drank the muddy streams; and when, to plead with Argus, she would try to stretch her arms, she had no arms to stretch. Would she complain, a moo came from her throat, a startling sound . . . as they thus grieved, Argus, star-eyed, drove off daughter from father, hurrying her away to distant pastures. Then himself, afar, high on a mountain top sat sentinel to keep his scrutiny on every side.But now heaven"s master could no more endure Phoronis" distress, and summoned his son , whom the bright shining Pleias bore, and charged him to accomplish Argus" death. Promptly he fastened on his ankle-wings, grasped in his fist the wand that charms to sleep, put on his magic cap, and thus arrayed Jove"s son sprang from his father"s citadel down to earth. There he removed his cap, laid by his wings; only his wand he kept.A herdsman now, he drove a flock of goats through the green byways, gathered as he went, and played his pipes of reed. The strange sweet skill charmed Juno"s guardian. ‘My friend,’ he called, ‘whoever you are, well might you sit with me here on this rock, and see how cool the shade extends congenial for a shepherd"s seat.’So Atlantiades joined him, and with many a tale he stayed the passing hours and on his reeds played soft refrains to lull the watching eyes. But Argus fought to keep at bay the charms of slumber and, though many of his eyes were closed in sleep, still many kept their guard. He asked too by what means this new design (for new it was), the pipe of reeds, was found. Then the god told this story . . .The tale remained untold; for Cyllenius saw all Argus" eyelids closed and every eye vanquished in sleep. He stopped and with his wand, his magic wand, soothed the tired resting eyes and sealed their slumber; quick then with his sword he struck off the nodding head and from the rock threw it all bloody, spattering the cliff with gore. Argus lay dead; so many eyes, so bright quenched, and all hundred shrouded in one night. Saturnia retrieved those eyes to set in place among the feathers of her bird and filled his tail with starry jewels."
Ovid, Metamorphoses 2. 531 :"Her peacocks, painted bright with Argus" eyes, lately slain."
Virgil, Aeneid 7. 791 (trans. Day-Lewis) (Roman epic C1st B.C.) :" Io, now changed to a heifer, with horns uplifted, and fought-haired--a potent symbol; also her guardian, Argus, and Inachus, her father, pouring out his stream from a graven pitcher."
Propertius, Elegies 1. 3 (trans. Goold) (Roman elegist C1st B.C.) :"I remained rooted with eyes intent upon her, like those of Argus upon the strange horns of Inachus" child ."
Valerius Flaccus, Argonautica 4. 365 (trans. Mozley) (Roman epic C1st A.D.) : "She accosts Jove thus : ‘Give me the untamed heifer that feeds on Argos" fertile plains and is just showing the horns of the infant moon; give her as a gift to thy dear bride. Myself now will I choose fit pastures and choicest fountains for my pet.’What ruse could Jove find to say her nay? What trickery, once found, could he have maintained? She, possessed of the gift, straightway sets Argus on guard; Argus as guardian pleases her, for everywhere on his head are sleepless eyes, as though a Lydian bride should bedeck her web with flecks of purple. At Argus" bidding must she go on paths unknown, over rocks, through monster-haunted wilds, tarrying oft, alas! And struggling with prayers and words fast locked within her breast . . . But she, when her limbs trembled aweary of her wandering or when now chilly evening sped down from heaven"s height--ah! How often laid she her body on a stone, or when long thirst made her faint, what pools did her lips drink, what pastures graze, how oft did her white shoulders quail before the lash! Nay, too, as daring death she planned to leap from some lofty height, swift did Argus drive her down to the vale beneath, and cruelly saved her at his queen"s behest: when on a sudden a hollow flute pipes out a measure of Arcady (Arcadia), and the winged Cyllenian , hastening to obey his sire, draws nigh, and tuning his oft reed to melody cries, ‘Wither away? Where roamest thou? Ho there! Give heed to my music!’ Following Argus close he notes that all his eyes are already languishing and seeking after sweet slumber, and in the midst of his song out he flashes his swift blade."
Statius, Thebaid 1. 253 ff (trans. Mozley) (Roman epic C1st A.D.) :" far-famed sceptre of great Phoroneus . . . there thou didst ruthelessly cast on sleep the guardian of the Pharian heifer ."
Statius, Thebaid 6. 275 ff :" Next in order is seen . . . Io, already prone and sorrow of her sire, sees behind her back Argus starred with eyes that no setting."
Statius, Silvae 5.4.1 (trans. Mozley) (Roman elegy C1st A.D) :"The thousand eyes of sacred Argus, which he kept but in alternate watchfulness, nor even waked in all his frame at once."
Nonnus, Dionysiaca 13. 27 ff (trans. Rouse) (Greek epic C5th A.D.) :"The immortal court of Zeus will not receive you without hard work, and the Horai (Horae) will not open the gates of Olympos to you unless you have struggled for the prize. Hermeias hardly could win his way to heaven, and only when he killed with his rod Argos the cowherd, sparkling with eyes from his feet to the hair of his head."
Nonnus, Dionysiaca 20. 35 ff :"You are not like a son of Zeus . . . you did not kill that unhappy lover bold Orion, nor Hera"s guardian Argos, the cowkeeper, a son of Gaia (Gaea the Earth) so fertile in evil, the spy on Zeus in his weddings with horned cattle!"