Acheron, Phlegethon, Cocytus, and Styx find their correspondence with the four rivers of Eden. As above, so below.
The rivers of Hades are synthesized in Lethe, where the lost souls drink to forget their subterranean journey and devolve within oblivion. This especially occurs after the Second Death, when initiating a new cycle within the elementary mineral kingdom, to reconquer what they have lost.
We must use the ark to cross the rivers of Hades and investigate our own infernos. Charon, a poetic form of χαρωπός (charopós), signifies "of keen gaze.” We must use our discriminating, conscious perception when investigating hell, so as not to become confused and enter oblivion.
The solar gods, the warriors of Mars, emerge victorious like Achilles from the rivers of transmutation. However, even the solar gods have their weakness in the heel, a symbol of Yesod, for if they fornicate and enter animal generation, they become as Samson in the Book of Judges, failures.
For thirty years I sought God. But when I looked carefully I found that in reality God was the seeker and I the sought. -Bayazid al-Bastami