Phaedo

Phaedo. Now these streams are many and great and of all sorts, but among the many are four streams, the greatest and outermost of which is that called Oceanus, which flows round in a circle, and opposite this, flowing in the opposite direction, is Acheron, which flows through various desert places and, passing under the earth, comes to the Acherusian lake. To this lake the souls of most of the dead go and, after remaining there the appointed time, which is for some longer and for others shorter, are sent back to be born again into living beings. The third river flows out between these two, and near the place whence it issues it falls into a vast region burning with a great fire and makes a lake larger than our Mediterranean sea, boiling with water and mud. Thence it flows in a circle, turbid and muddy, and comes in its winding course, among other places, to the edge of the Acherusian lake, but does not mingle with its water. Then, after winding about many times underground, it flows into Tartarus at a lower level. This is the river which is called Pyriphlegethon, and the streams of lava which spout up at various places on earth are offshoots from it. Opposite this the fourth river issues, it is said, first into a wild and awful place, which is all of a dark blue color, like lapis lazuli. This is called the Stygian river, and the lake which it forms by flowing in is the Styx. And when the river has flowed in here and has received fearful powers into its waters, it passes under the earth and, circling round in the direction opposed to that of Pyriphlegethon, it meets it coming from the other way in the Acherusian lake. And the water of this river also mingles with no other water, but this also passes round in a circle and falls into Tartarus opposite Pyriphlegethon. And the name of this river, as the Poets say, is Cocytus. Such is the nature of these things. Now when the dead have come to the place where each is led by his genius, first they are judged and sentenced, as they have lived well and piously, or not. And those who are found to have lived neither well nor ill, go to the Acheron and, embarking upon vessels provided for them, arrive in them at the lake; there they dwell and are purified, and if they have done any wrong they are absolved by paying the penalty for their wrong doings, and for their good deeds they receive rewards, each according to his merits. But those who appear to be incurable, on account of the greatness of their wrongdoings, because they have committed many great deeds of sacrilege, or wicked and abominable murders, or any other such crimes, are cast by their fitting destiny into Tartarus, whence they never emerge.