Tertullian

“ Therefore, if the mere nature of water, in that it is the appropriate material for washing away, leads men to flatter themselves with a belief in omens of purification, how much more truly will waters render that service through the authority of God, by whom all their nature has been constituted! If men think that water is endued with a medicinal virtue by religion, what religion is more effectual than that of the living God? ”

“ Lest any think it too hard for belief that a holy angel of God should grant his presence to waters, to temper them to man’s salvation; while the evil angel holds frequent profane commerce with the selfsame element to man’s ruin. If it seems a novelty for an angel to be present in waters, an example of what was to come to pass has forerun. An angel, by his intervention, was wont to stir the pool at Bethsaida. [10] They who were complaining of ill-health used to watch for him; for whoever had been the first to descend into them, after his washing, ceased to complain. ”

“ Witness all shady founts, and all unfrequented brooks, and the ponds in the baths, and the conduits [6] in private houses, or the cisterns and wells which are said to have the property of “spiriting away,” [7] through the power, that is, of a hurtful spirit. Men whom waters have drowned [8] or affected with madness or with fear, they call nymph-caught, [9] or “lymphatic,” or “hydro-phobic.” ”