6 Of all these, however, the principle is the same, which misleads and deceives, and with tricks which darken the truth, leads away a credulous and foolish rabble. They are impure and wandering spirits, who, after having been steeped in earthly vices, have departed from their celestial vigour by the contagion of earth, and do not cease, when ruined themselves, to seek the ruin of others; and when degraded themselves, to infuse into others the error of their own degradation. These demons the poets also acknowledge, and Socrates declared that he was instructed and ruled at the will of a demon; and thence the Magi have a power either for mischief or for mockery, of whom, however, the chief Hostanes both says that the form of the true God cannot be seen, and declares that true angels stand round about His throne. Wherein Plato also on the same principle concurs, and, maintaining one God, calls the rest angels or demons. Moreover, Hermes Trismegistus speaks of one God, and confesses that He is incomprehensible, and beyond our estimation.
Source: The Treatises of Cyprian (New Advent)