“[In the world below…] those who appear to have lived neither well not ill, go to the river Acheron, and mount such conveyances as they can get, and are carried in them to the lake, and there they dwell and are purified of their evil deeds, and suffer the penalty of the wrongs which they have done to others, and are absolved, and receive the rewards of their good deeds according to their deserts. But those who appear to be incurable by reason of the greatness of their crimes—who have committed many and terrible deeds of sacrilege, murders foul and violent, or the like—such are hurled into Tartarus, which is their suitable destiny, and they never come out. Those again who have committed crimes, which, although great, are not unpardonable—who in moment of anger, for example, have done violence to a father or a mother, and have repented for the remainder of their lives, or who have taken the life of another under like extenuating circumstances—these are plunged into Tartarus, the pains of which they are compelled to undergo for a year, but at the end of the year the wave casts them forth—mere homicides by way of Cocytus, patricides and matricides by Pyriphlegethon—and they are borne to the Acherusian Lake, and here they lift up their voices and call upon the victims whom they have slain or wronged, to have pity on them, and to receive them, and to let them come out of the river into the lake. And if they prevail, then they come forth and cease from their troubles; but if not, they are carried back again into Tartarus and from thence into the rivers unceasingly, until they obtain mercy from those whom they have wronged: for this is the sentence inflicted upon them by their judges.”

Plato, Phaedo