The River Lethe was one of the five rivers of Hades. The River Lethe was also known as the Ameles Potamos (river of unmindfulness). All who drank from it experienced complete forgetfulness. Lethe was also the name of the Greek spirit of forgetfulness and oblivion, with whom the river was identified.
In Classical Greek, the word “Lethe” means oblivion, forgetfulness, or concealment. It is related to the Greek term for truth, “aletheia,” meaning “unforgetfulness.”
The five rivers of Hades were:
Styx: river of hate.
Akheron: river of sorrow.
Kokytos: the river of lamentation.
Plegethon: river of fire.
Lethe: river of forgetfulness and oblivion.
According to Statius, the River Lethe bordered Elysium, the final resting place of the virtuous. Ovid wrote that the River Lethe flowed through the cave of Hypnos, the god of sleep, where its murmuring would induce drowsiness.
The shades of the dead were required to drink from the River Lethe in order to forget their earthly life. In the Aenid, Virgil wrote that only after the dead had their memories erased by the Lethe could they be reincarnated.
The goddess Lethe was the personification of forgetfulness and oblivion. Hesiod’s Theogony identifies her as the daughter of Eris (strife), and the sister of Ponos (toil), Limos (starvation), Algea (pains), the Hysminai (fightings), the Makhai (battles), the Phonoi (murders), the Androktasiai (manslaughters), the Neikea (quarrels), the Pseudologoi (lies), the Amphilogiai (disputes), Dysnomia (lawless), Atë (ruin), and Horkos (oath).
The Myth of Er at the end of Plato’s Republic describes the dead arriving at the Plain of Lethe, through which the River Ameles (careless) runs. Mystery religions taught the existence of the River Mnemosyne: those who drank from this river would attain omniscience and remember everything. Initiates were taught that they would have a choice of rivers from which to drink after death, and they were taught that they should elect to drink from the River Mnemosyne instead of Lethe.
References to the two rivers derive from verse inscriptions on gold plates from Thuri in Southern Italy. There were rivers of Lethe and Msemosyne at the oracular shrine of Trophonius in Boeotia, from which worshippers would drink before seeking oracular consultations with the god.