(Canto 9, line 38)
The three Furies are: Alecto, the never resting; Megaera, the grudging; and Tisiphone, the vengeful. In Greek mythology, they were goddesses of vengeance, pursuing and punishing those who have committed certain ill deeds like killing or breaking oaths. Tradition holds that they turned black when angered, but were normally white. The Furies are often mentioned in classic literature, and figure for example in the works of Virgil, Ovid and Stasius. They are the Roman version of a corresponding Greek group of divinities called the Erinyes - which is how Virgil terms them in the poem - born of the river Akhenaton and Nyx, the night goddess. Dante calls them "handmaids of the Queen of everlasting lamentation" - the Queen would refer to Persephone or her Roman equivalent Proserpina, married to Hades/Pluto.