In respect, however, to this concupiscence of the flesh, we have striven in this lengthy discussion to distinguish it accurately from the goods of marriage. This we have done on account of our modern heretics, who cavil whenever concupiscence is censured, as if it involved a censure of marriage. Their object is to praise concupiscence as a natural good, that so they may defend their own baneful dogma, which asserts that those who are born by its means do not contract original sin. Now the blessed Ambrose, bishop of Milan, by whose priestly office I received the washing of regeneration, briefly spoke on this matter, when, expounding the prophet Isaiah, he gathered from him the nativity of Christ in the flesh: |Thus,| says the bishop, |He was both tempted in all points as a man, and in the likeness of man He bare all things; but inasmuch as He was born of the Spirit, He kept Himself from sin. For every man is a liar; and there is none without sin but God alone. It has, therefore, been ever firmly maintained, that it is clear that no man from husband and wife, that is to say, by means of that conjunction of their persons, is free from sin. He who is free from sin is also free from conception of this kind.| Well now, what is it which St. Ambrose has here condemned in the true doctrine of this deliverance? -- is it the goodness of marriage, or not rather the worthless opinion of these heretics, although they had not then come upon the stage? I have thought it worth while to adduce this testimony, because Pelagius mentions Ambrose with such commendation as to say: |The blessed Bishop Ambrose, in whose writings more than anywhere else the Roman faith is clearly stated, has flourished like a beautiful flower among the Latin writers. His fidelity and extremely pure perception of the sense of Scripture no opponent even has ever ventured to impugn.| I hope he may regret having entertained opinions opposed to Ambrose, but not that he has bestowed this praise on that holy man.
Here, then, you have my book, which, owing to its tedious length and difficult subject, it has been as troublesome for me to compose as for you to read, in those little snatches of time in which you have been able (or at least, as I suppose, have been able) to find yourself at leisure. Although it has been indeed drawn up with considerable labour amidst my ecclesiastical duties, as God has vouchsafed to give me His help, I should hardly have intruded it on your notice, with all your public cares, if I had not been informed by a godly man, who has an intimate knowledge of you, that you take such pleasure in reading as to lie awake by the hour, night after night, spending the precious time in your favourite pursuit.