Ante-Nicene Fathers, Vol VIII:
Pseudo-Clementine Literature.: Chapter V

Chapter V.—Theory of Magic.

“Then Appion said:  ‘Admit that I know more of these things than you do.  However, that you may not think that there is nothing in what you have heard from me in reference to what you have said, I will tell you how the demons are under necessity to obey the magicians in the matters about which they are commanded.  For as it is impossible for a soldier to contradict his general, and impossible for the generals themselves to disobey the king—for if any one oppose those set over him, he is altogether deserving of punishment—so it is impossible for the demons not to serve the angels who are their generals; and when they are adjured by them, they yield trembling, well knowing that if they disobey they shall be fully punished.  But the angels also themselves, being adjured by the magicians in the name of their ruler, obey, lest, being found guilty of disobedience, they be destroyed.  For unless all things that are living and rational foresaw vengeance from the ruler, confusion would ensue, all revolting against one another.’