Plato now turns to a discussion of what happens to souls after death. They have guardian spirits who lead them on the path to Hades, though sinful souls sometimes linger, unwilling to move on.
This brings Plato to a brief discussion of the earth. He maintains that it is a spherical body, held in place by a kind of cosmic equipoise, since there is no reason for it to incline in one direction or another. The theory of equipoise or equilibrium is like that of Anaximander who, however, believed in a disk-shaped earth like most early Greek cosmologists. A spherical earth would have its weight equally distributed in all directions, unlike a disk-shaped earth. The earth is of great size, according to Plato, and has many hollows. Humans are like ants or frogs in a great marsh. If one could travel to the limits of the atmosphere, one would see the true shape and nature of the earth. Seen from above, the earth would like a patchwork ball of different colors and materials.[21]
Inside the earth are great caverns into which flow rivers of water, mud, and fire, including streams of lava such as those found in Sicily, where Plato had recently traveled. On the outside of the earth flows Ocean. The river Acheron flows into a great lake, where many souls of the dead gather. The river Pyriphlegethon, “Burning Fire,” flows from near Acherusian “Woeful” Lake into Tartarus in the middle of the earth, consisting of fire and boiling water and mud. There is a river called Stygion “Abominable” that empties into Lake Styx. And finally there is a river Cocytus “Wailing” that flows into Tartarus opposite to the Pyriphlegethon.[22] Here Plato is offering an account of the afterlife and a geography of the underworld replete with the rivers of mythology. There is a judgment of souls, after which those who have lived decent lives dwell about the Acherusian Lake, with a kind of Purgatory for lesser sins. Those guilty of violent crimes and murder are cast in Tartarus, Plato’s inferno, after which those deemed curable emerge to beg their victims for forgiveness; if they receive it, they are released from punishment; otherwise, they are sent back to Tartarus. People having lived a pious life are released to the surface of the earth in beautiful surroundings. Those who have perfected themselves through philosophy escape the cycle of reincarnations and life forever after without the encumbrance of a body.
Plato has now gone far beyond the bounds of Socratic philosophy, which is restricted to discussions of moral philosophy, and speculated about cosmography, meteorology, geology, and eschatology, with a hint of theology. Plato has posited a spherical earth, complete with an underworld populated by departed souls, where rewards and punishments are meted out based on the lives lived in mortality. Plato’s Inferno will become a model for depictions of the afterlife in Virgil, Dante, and others. Plato’s nascent cosmology shows a strong commitment to a moral order that is realized within the natural order of the cosmos. Will philosophy be able to fuse ethics with cosmology, and cosmology with theology? Later Platonists, including Plotinus, will see this development as a critical advance in philosophy.
[21] Plato Phaedo 109a-111c.
[22] Plato Phaedo 111c-113c.