In Roman mythology, the Manes were the souls of deceased loved ones. As minor spirits, they were similar to the Lares, Genii and Di Penates. They were honored during the Parentalia and Feralia in February.
The Manes were also called the Di Manes (Di meaning "Gods"), and Roman tombstones often included the letters D.M., which stood for dis manibus, or "dedicated to the Manes-gods". The word was also used as a metaphor to refer to the underworld.
Manes is derived from "an archaic adjective manus-'good'- which was the opposite of immanis"..
The Manes were offered blood sacrifices. The gladiatorial games, originally held at funerals, may have been instituted in the honor of the Manes.
The "flowing stone"..must not be confused with the stone of the same name which, according to Festus, was the gateway to the underworld.
Bailey (1907) states:
There is, for instance, what anthropology describes as 'sympathetic magic'—the attempt to influence the powers of nature by an imitation of the process which it is desired that they should perform. Of this we have a characteristic example in the ceremony of the aquaelicium, designed to produce rain after a long drought. 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.