"an eagle, a vulture, for ever tearing the liver out"
Prometheus - from a painting by Moreau (1868)
Public DomainPrometheus - from a painting by Moreau (1868) - Credit: Gustave Moreau (1826-1898)
This is a reference to the story  in Greek mythology of Prometheus, one of the Titans (powerful gods), who brought fire to the mortals. Zeus (King of the gods) punished him by having him bound to a rock where his liver was eaten daily by an eagle.