John Cassian, Conferences I–X VIII.14: How it is that spiritual wickednesses obtained the names of powers or principalities

We can then see clear reasons, in addition to those ideas which we expounded above, why they are called principalities or powers; viz., because they rule and preside over different nations, and at least hold sway over inferior spirits and demons, of which the gospels give us evidence by their own confession that there exist legions. For they could not be called lords unless they had some over whom to exercise the sway of lordship; nor could they be called powers or principalities, unless there were some over whom they could claim power: and this we find pointed out very clearly in the gospel by the Pharisees in their blasphemy: “He casteth out devils by Beelzebub the prince of the devils,” for we find that they are also called “rulers of darkness,” and that one of them is styled “the prince of this world.” But the blessed Apostle declares that hereafter, when all things shall be subdued to Christ, these orders shall be destroyed, saying: “When He shall have delivered up the kingdom to God even the Father, when He shall have destroyed all principalities and powers and dominions.” And this certainly can only take place if they are removed from the sway of those over whom we know that powers and dominions and principalities take charge in this world.