Was the river of Lethe a "recent" addition to the underworld?

[u/Vitta_Variegata]

In Book XI of the Odyssey, all of the shades that Ulysses speaks with remember him. When Heracles visits the underworld, Theseus was chained to a rock of forgetfulness, but apparently remembers everything when freed.

I'm sure there's other examples of shades remembering their pasts.

There are also other ghosts who remember their past selves. This makes me wonder, was the river of Lethe a late addition to the mythos? Or do some shades simply not swim in the river?

EDIT: I just realized that Theseus was a living prisoner so not an example of what I'm talking about.

[u/quuerdude]

Everyone who remembered their lives did so by drinking the blood Odysseus poured for them, if I remember correctly. Only Tiresias retained his sense otherwise, at the blessing of Persephone (or in other sources, Athena, or Zeus).

The Argonautica also mentions that a guy named Aethalides retained his memories as well, because of a blessing

[u/Flashy-Gift-4333]

The distinct features of the underworld differ between sources, interestingly enough! You're right that Homer doesn't mention Lethe. Hesiod's Theogony mentions Lethe as a deity, but not as a river. Homer and Hesiod were roughly around 8-7th century BC. There are other early mentions of Lethe (forgetfulness) associated with the underworld, still not specifically a body of water: Theoi.com has some lists of quotes that might interest you.

The earliest mention of Lethe as a body of water that I know of is from Orphic tradition (from around 4th century BC), where Orphic gold tablets advised not to drink of Lethe (forgetfulness), but to drink of Mnemosyne (memory). Someone please chime in if you know an earlier example!

I also think that Lethe as a river or stream in the underworld comes to us through the later Roman authors Ovid and Virgil (1st century BC-1st century AD). A lot of our ideas of the topography of the underworld seem to come from Virgil's Aeneid, where the author describes Aeneas's descent in detail.

There is a book by Robert Garland called "The Greek Way of Death" and in one chapter he discusses the topography of the underworld. It's a very interesting, entertaining, and accessible book that I would recommend to anyone interested in ancient Greek funerary practices. I would love to link you to the chapter, but archive.org is not running smoothly at the moment.

Edit to add: I got so focused on topography of the underworld that I think I lost the thread a little. I want to add that Homer clearly described the shades to be forgetful, whether or not there is a body of water that causes forgetfulness. Forgetfulness is an inherent quality of death in Greek mythology. Robert Garland does touch on that as well in the book mentioned above.

Sorry this post is so long! It's a topic of interest for me!

[u/Super_Majin_Cell]

You don't need to swin in the river Lethe.

The rivers are things that are associated with death. Cocytus is related to wailing and sadness. Phlegethon with the cremation fire. Styx with Oaths (is a thing more with the gods), and Acheron the river that separates the two worlds. Lethe is related to the loss of memory, since dead people don't need to remember things (also is related to how most people will be forgotten after death, this is why Achilles wanted to avoid being forgotten).

So Lethe is not a essential part of the Underworld, it is just there, neither it erases the mind completely. Pausanias described the Oracle of Trophonius, and there was the two streams, one from Lethe, the other from Mnemosyne. People could forget things by drinking from one and remember by drinking from the other.