26 But it has been clearly enough intimated, that by the judgment of God these things befell them through the instrumentality of evil angels, in this wicked world, as though it were in Egypt and in the plain of Thanis, where we ought to be humble, until there come that world, wherein we may earn to be exalted out of this humiliation. For even Egypt in the Hebrew tongue does signify darkness or tribulations, in which tongue, Thanis, as I have observed, is understood to be humble commandment.
Concerning the evil angels therefore in this Psalm, while he was speaking of those very plagues, there has been something inserted, which must not be passed over cursorily: “He sent upon them,” he says, “an infliction through evil angels.” Now that the devil and his angels are so very evil, that for them everlasting fire is prepared, no believer is ignorant: but that there should be sent by means of them an infliction from the Lord God upon certain whom He judges to be deserving of this punishment, seems to be a hard thing to those who are little prone to consider, how the perfect justice of God does use well even evil things.
For these indeed, as far as regards their substance, what other person but Himself has made? But evil He has not made them: yet He does use them, inasmuch as He is good, well, that is, conveniently and justly: just as on the other hand unrighteous men do use His good creatures in evil manner. God therefore does use evil angels not only to punish evil men, as in the case of all those concerning whom the Psalm does speak, as in the case of king Achab, whom a spirit of lying by the will of God did beguile, in order that he might fall in war: but also to prove and make manifest good men, as He did in the case of Job.
But as far as regards that corporal matter of visible elements, I suppose that thereof angels both good and evil are able to make use, according to the power given to each: just as also men good and evil do use such things, as far as they are able, according to the measure of human infirmity. For we use both earth and water, and air, and fire, not only in things necessary for our support, but also in many operations superfluous and playful, and marvellously artificial. For countless things, which are called μηχανήματα, are moulded out of these elements scientifically employed.
But over these things angels have a far more extended power, both the good and the evil, though greater is that which the good have; but only so far as is commanded or permitted by the will and providence of God; on which terms also we have it. For not even in these cases are we able to do all that we will. But in a book the most unerring we read that the devil was able even to send fire from Heaven, to burn up with wonderful and awful fierceness so great a number of the cattle of a holy man: which thing no one of the faithful would dare perchance to ascribe to the devil, except it were read on the authority of Holy Scripture.
But that man, being by the gift of God just and firm, and of godly knowledge, says not, The Lord has given, the devil has taken away: but, “The Lord has given, the Lord has taken away:” very well knowing that even what the devil was able to do with these elements, he would still not have done to a servant of God, except at his Lord's will and permission; he did confound the malice of the devil, forasmuch as he knew who it was that was making use thereof to prove him. In the sons then of unbelief like as it were in his own slaves, he does work, like men with their beasts, and even therewith only so far as is permitted by the just judgment of God.
But it is one thing when his power is restrained from treating even his own as he pleases, by a greater power; another thing when to him power is given even over those who are alien from him. Just as a man with his beast, as men understand it, does what he will, and yet does not indeed, if he be restrained by a greater power: but with another man's beast to do something, he does wait until power be given from him unto whom it belongs. In the former case the power which there was is restrained, in the latter that which there was not is conceded.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)