there were always eyes still awake. Argus was Hera 's servant. His great service to the Olympic pantheon was to slay the chthonic serpent-legged monster Echidna as she slept in her cave (Homer, Iliad ii.783; Hesiod, Theogony, 295ff; Apollodorus, ii.i.2). Hera's last task for Argus was to guard a white heifer