Manes

They belonged broadly to the category of di inferi, "those who dwell below",[1] the undifferentiated collective of divine dead.

The theologian St. Augustine, writing about the subject a few centuries after most of the Latin pagan references to such spirits, differentiated Manes from other types of Roman spirits: Apuleius "says, indeed, that the souls of men are demons, and that men become Lares if they are good, Lemures or Larvae if they are bad, and Manes if it is uncertain whether they deserve well or ill...

[5] Roman tombstones often included the letters D.M., which stood for Dis Manibus, literally "to the Manes",[6] or figuratively, "to the spirits of the dead", an abbreviation that continued to appear even in Christian inscriptions.

[5] When a new town was founded, a round hole would be dug and a stone called a lapis manalis would be placed in the foundations, representing a gate to the underworld.

In classical times the ceremony consisted in a procession headed by the pontifices, which bore the sacred rain-stone from its resting-place by the Porta Capena to the Capitol, where offerings were made to the sky-deity, Iuppiter, but from the analogy of other primitive cults and the sacred title of the stone (lapis manalis), it is practically certain that the original ritual was the purely imitative process of pouring water over the stone.