The Divine Institutes

When, therefore, the number of men had begun to increase, God in His forethought, lest the devil, to whom from the beginning He had given power over the earth, should by his subtilty either corrupt or destroy men, as he had done at first, sent angels for the protection and improvement of the human race; and inasmuch as He had given these a free will, He enjoined them above all things not to defile themselves with contamination from the earth, and thus lose the dignity of their heavenly nature. He plainly prohibited them from doing that which He knew that they would do, that they might entertain no hope of pardon. Therefore, while they abode among men, that most deceitful ruler of the earth, by his very association, gradually enticed them to vices, and polluted them by intercourse with women. Then, not being admitted into heaven on account of the sins into which they had plunged themselves, they fell to the earth. Thus from angels the devil makes them to become his satellites and attendants. But they who were born from these, because they were neither angels nor men, but bearing a kind of mixed nature, were not admitted into hell, as their fathers were not into heaven. Thus there came to be two kinds of demons; one of heaven, the other of the earth. The latter are the wicked spirits, the authors of all the evils which are done, and the same devil is their prince. Whence Trismegistus calls him the ruler of the demons. But grammarians say that they are called demons, as though dœmones, that is, skilled and acquainted with matters: for they think that these are gods. They are acquainted, indeed, with many future events, but not all, since it is not permitted them entirely to know the counsel of God; and therefore they are accustomed to accommodate their answers to ambiguous results. The poets both know them to be demons, and so describe them. Hesiod thus speaks:—

And this is said for this purpose, because God had sent them as guardians to the human race; but they themselves also, though they are the destroyers of men, yet wish themselves to appear as their guardians, that they themselves may be worshipped, and God may not be worshipped. The philosophers also discuss the subject of these beings. For Plato attempted even to explain their natures in his “Banquet;” and Socrates said that there was a demon continually about him, who had become attached to him when a boy, by whose will and direction his life was guided. The art also and power of the Magi altogether consists in the influences of these; invoked by whom they deceive the sight of men with deceptive illusions, so that they do not see those things which exist, and think that they see those things which do not exist. These contaminated and abandoned spirits, as I say, wander over the whole earth, and contrive a solace for their own perdition by the destruction of men. Therefore they fill every place with snares, deceits, frauds, and errors; for they cling to individuals, and occupy whole houses from door to door, and assume to themselves the name of genii; for by this word they translate demons in the Latin language. They consecrate these in their houses, to these they daily pour out libations of wine, and worship the wise demons as gods of the earth, and as averters of those evils which they themselves cause and impose. And these, since spirits are without substance and not to be grasped, insinuate themselves into the bodies of men; and secretly working in their inward parts, they corrupt the health, hasten diseases, terrify their souls with dreams, harass their minds with phrenzies, that by these evils they may compel men to have recourse to their aid.