Ante-Nicene Fathers, Vol VII:
Lactantius: Chap. XXVIII.—Of the demons, and their evil practices

Chap. XXVIII.—Of the Demons, and Their Evil Practices.

These are the demons, of whom the poets often speak in their poems, whom Hesiod calls the guardians of men. For they so persuaded men by their enticements and deceits, that they believed that the same were gods. In fine, Socrates used to give out that he had a demon as the guardian and director of his life from his first childhood, and that he could do nothing without his assent and command. They attach themselves, therefore, to individuals, and occupy houses under the name of Genii or Penates. To these temples are built, to these libations are daily offered as to the Lares, to these honour is paid as to the averters of evils. These from the beginning, that they might turn away men from the knowledge of the true God, introduced new superstitions and worship of gods. These taught that the memory of dead kings should be consecrated, temples be built, and images made, not that they might lessen the honour of God, or increase their own, which they lost by sinning, but that they might take away life from men, deprive them of the hope of true light, lest men should arrive at that heavenly reward of immortality from which they fell. They also brought to light astrology, and augury, and divination; and though these things are in themselves false, yet they themselves, the authors of evils, so govern and regulate them that they are believed to be true. They also invented the tricks of the magic art, to deceive the eyes. By their aid it comes to pass, that that which is appears not to be, and that which is not appears to be. They themselves invented necromancies, responses, and oracles, to delude the minds of men with lying divination by means of ambiguous issues. They are present in the temples and at all sacrifices; and by the exhibition of some deceitful prodigies, to the surprise of those who are present, they so deceive men, that they believe that a divine power is present in images and statues. They even enter secretly into bodies, as being slight spirits; and they excite diseases in the vitiated limbs, which when appeased with sacrifices and vows they may again remove. They send dreams either full of terror, 1485 that they themselves may be invoked, or the issues of which may correspond with the truth, that they may increase the veneration paid to themselves. Sometimes also they put forth something of vengeance against the sacrilegious, that whoever sees it may become more timid and superstitious. Thus by their frauds they have drawn darkness over the human race, that truth might be oppressed, and the name of the supreme and matchless God might be forgotten.  

Footnotes

Plena terroris. Another reading is, “aut plane terrores.”