Lethe (Λήθη) & Eunoe (Εύνοε) ===== In traditional Greek mythology, there are five rivers in Hades, the Greek underworld: Lethe (forgetfulness), Styx (hate), Acheron (sorrow), Cocytus (lamentation), and Phlegethon (fire). Lethe played an important role in the Greek underworld: souls of the dead were required to drink from Lethe in order to forget their earthly lives. In *Aeneid*, Virgil defines this act as a critical step for souls to be reincarnated. In *Purgatorio*, the second part of *The Divine Comedy* (*Divina Commedia*), Dante describes Cocytus as a lake, and intoduces **Eunoe** as the fifth river. Eunoe is a neologism derived from the Greek *eu-* (good) and *noe* (mind). As penitents reach the Garden of Eden at the top of Mount Purgatory, they are washed in Lethe and Eunoe—in that order. In Dante's version, Lethe's draught causes souls to forget the memories of their mortal sins. Eunoe, in turn, strengthens the memories of good deeds. Thus cleansed, souls are ready to enter Heaven.