On Marriage and Concupiscence

This wound which the devil has inflicted on the human race compels everything which has its birth in consequence of it to be under the devil's power, as if he were rightly plucking fruit off his own tree. Not as if man's nature, which is only of God, came from him, but sin alone, which is not of God. For it is not on its own account that man's nature is under condemnation, because it is the work of God, and therefore laudable; but on account of that condemnable corruption by which it has been vitiated.

Now it is by reason of this condemnation that it is in subjection to the devil, who is also in the same damnable state. For the devil is himself an unclean spirit: good, indeed, so far as he is a spirit, but evil as being unclean; for by nature he is a spirit, by the corruption thereof an unclean one. Of these two, the one is of God, the other of himself. His hold over men, therefore, whether of an advanced age or in infancy, is not because they are human, but because they are polluted.

He, then, who feels surprise that God's creature is a subject of the devil, should cease from such feeling. For one creature of God is in subjection to another creature of God, the less to the greater, a human being to an angelic one; and this is not owing to nature, but to a corruption of nature: polluted is the sovereign, polluted also the subject. All this is the fruit of that ancient stock of pollution which he has planted in man; himself being destined to suffer a heavier punishment at the last judgment, as being the more polluted; but at the same time even they who will have to bear a less heavy burden in that condemnation are subjects of him as the prince and author of sin, for there will be no other cause of condemnation than sin.