Porphyry, fragment of On the Philosophy to be derived from Oracles preserved in Eusebius, Praeparatio Evangelica 4.22
Among the Egyptians also, and the Phoenicians, and generally among those who are wise in divine things, thongs are violently cracked in the temples, and animals are dashed against the ground before worshipping the Gods, the priests thus driving away these daemons by giving them the breath or blood of animals, and by the beating of the air, in order that on their departure the presence of the God may be granted.
Every house also is full of them, and on this account, when they are going to call down (katakalôsin) the Gods, they purify the house first (prokathairousin), and cast these daemons out (ekballousi). Our bodies also are full of them, for they especially delight in certain kinds of food. So when we are eating they approach and sit close to our body; and this is the reason of the purifications (haigneiai), not chiefly on account of the Gods, but in order that these evil daemons may depart. But most of all they delight in blood and in impure meats, and enjoy these by entering into those who use them.
For universally the vehemence of the desire towards anything, and the impulse of the lust of the spirit, is intensified from no other cause than their presence: and they also force men to fall into inarticulate noises and flatulence by sharing the same enjoyment with them.
For where there is a drawing in of much breath, either because the stomach has been inflated by indulgence, or because eagerness from the intensity of pleasure breathes much out and draws in much of the outer air, let this be a clear proof to you of the presence of such spirits (pneumatôn) there. So far human nature ventures to investigate the snares that are set about it: for when the deity (ho theos) enters in, the breathing (pneuma) is much increased.