ARGUS1. Argos Panoptes, "all-eyed Argus," was so called because of his hundred eyes. Juno set him to guard Io, Jupiter's mistress, whom Jupiter had changed into a heifer to protect her from Juno's wrath. Argos tied her with a halter and fed her with bitter herbs. Jupiter decided to release Io from her torment. He commanded Mercury to slay Argos, an almost impossible task since the hundred eyes were never all closed at the same time. Mercury, however, charmed Argos to sleep with his magic wand and his flute music. When all the eyes were closed, he beheaded Argos and escaped with Io. Juno placed the eyes in the tail of her favorite bird, the peacock (Met I.668-723; OM I.3448-3752). The watchfulness of the hundred eyes became proverbial.
Mercury, dressed as he was when he slew Argus, appears to Arcite, KnT 1389-1390; that is, he wears his magic cap and his winged sandals and carries his magic wand. Not even Argus with his hundred eyes can keep watch on Alys, WBP 358. Despite his hundred eyes, with which he could examine closely and pry into matters, Argus was blinded, MerchT 2111. Troilus calls Calcas "Argus-eyed," Tr IV.1459. [Alisoun3: Arcita: Mercurie]