20 To say, as I have done, that virginity is cleaner than wedlock, that the even numbers must give way to the odd, that the types of the Old Testament establish the truth of the Gospel: this, it appears, is a great sin subversive of the churches and intolerable to the world. The remaining points which are censured in my treatise are, I take it, of less importance, or else resolve themselves into this. I have, therefore, refrained from answering them, both that I may not exceed the limit at my disposal, and that I may not seem to distrust your intelligence, knowing as I do that you are ready to be my champion even before I ask you. With my last breath, then, I protest that neither now nor at any former time have I condemned marriage. I have merely answered an opponent without any fear that they of my own party would lay snares for me. I extol virginity to the skies, not because I myself possess it, but because, not possessing it, I admire it all the more. Surely it is a modest and ingenuous confession to praise in others that which you lack yourself. The weight of my body keeps me fixed to the ground, but do I fail to admire the flying birds or to praise the dove because, in the words of Virgil, it
Glides on its liquid path with motionless swift wings?
Let no man deceive himself, let no man, giving ear to the voice of flattery, rush upon ruin. The first virginity man derives from his birth, the second from his second birth. The words are not mine; it is an old saying, “No man can serve two masters;” that is, the flesh and the spirit. For “the flesh lusts against the spirit, and the spirit against the flesh; and these are contrary the one to the other,” so that we cannot do the things that we would. When, then, anything in my little work seems to you harsh, have regard not to my words, but to the Scripture, whence they are taken.
Source: Letters (New Advent)