Some take so much pleasure in hatred and the revenge it inspires that they are not content simply to kill the body but long to destroy the soul as well, although the Lord redeems the soul. They are lowered though a dark hole toward the bowels of the earth, the depth to which they go being determined by the intensity of their hatred and the vengefulness growing out of it. A dreadful terror and horror then strike them, while they are being held in the grip of their lust for revenge. As that desire grows, they slip even farther down.
Later they are sent to a place beneath Gehenna, where big, terrifying, round-bellied snakes appear, as lifelike as if they actually existed. They torture the vengeful spirits with their bites, which the spirits experience just as vividly as they do the snakes. Spirits feel these sensations—corresponding as they do to the spirits’lives—as keenly as people living in the body feel bodily sensation.
Meanwhile they live out their dreadful fantasies, wallowing in them for ages, until they no longer know that they were once human. By no other method can the way of life that they acquired from such acts of hatred and revenge be extinguished.
from Secrets of Heaven, Volume 1, Section 815