The phrase “Argus eyed” means extraordinarily vigilant. This, too, comes from Greek mythology.
The goddess Hera, wife of the supreme god Zeus, jealous of his affection for the nymph Io, turned her into a cow and then appointed Argus, possessed of a hundred eyes and able to see in all directions, as guardian and caretaker.
Notwithstanding this precaution, Zeus had his messenger, Hermes, kill the hundred-eyed Argus, whose eyes were thereupon transferred to the tail of the peacock.
