1 Although I suppose that, before this reaches you, you have received through our son the deacon Cyprian, a servant of God, the letter which I sent by him, from which you would be apprised with certainty that I wrote the letter of which you mentioned that a copy had been brought to you; in consequence of which I suppose that I have begun already, like the rash Dares, to be beaten and belaboured by the missiles and the merciless fists of a second Entellus in the reply which you have written; nevertheless I answer in the meantime the letter which you have deigned to send me by our holy son Asterius, in which I have found many proofs of your most kind goodwill to me, and at the same time some signs of your having in some measure felt agrieved by me. In reading it, therefore, I was no sooner soothed by one sentence than I was buffeted in another; my wonder being especially called forth by this, that after alleging, as your reason for not rashly accepting as authentic the letter from me of which you had a copy, the fact that, offended by your reply, I might justly remonstrate with you, because you ought first to have ascertained that it was mine before answering it, you go on to command me to acknowledge the letter frankly if it is mine, or send a more reliable copy of it, in order that we may, without any bitterness of feeling, address ourselves to the discussion of scriptural doctrine. For how can we engage in such discussion without bitterness of feeling, if you have made up your mind to offend me? Or, if your mind is not made up to this, what reason could I have had, when you did not offend me, for justly complaining as having been offended by you, that you ought first to have made sure that the letter was mine, and only then to have replied, that is to say, only then to have offended me? For if there had been nothing to offend me in your reply, I could have had no just ground of complaint. Accordingly, when you write such a reply to that letter as must offend me, what hope is left of our engaging without any bitterness in the discussion of scriptural doctrine? Far be it from me to take offense if you are willing and able to prove, by incontrovertible argument, that you have apprehended more correctly than I have the meaning of that passage in Paul's Epistle [to the Galatians], or of any other text in Holy Scripture: nay, more, far be it from me to count it anything else than gain to myself, and cause of thankfulness to you, if in anything I am either informed by your teaching or set right by your correction.
2. But, my very dear brother, you could not think that I could be offended by your reply, had you not thought that you were offended by what I had written. For I could never have entertained concerning you the idea that you had not felt yourself offended by me if you so framed your reply as to offend me in return. If, on the other hand, I have been supposed by you to be capable of such preposterous folly as to take offense when you had not written in such a way as to give me occasion, you have in this already wronged me, that you have entertained such an opinion of me. But surely you who are so cautious, that although you recognised my style in the letter of which you had a copy, you refused to believe its authenticity, would not without consideration believe me to be so different from what your experience has proved me to be. For if you had good reason for seeing that I might justly complain had you hastily concluded that a letter not written by me was mine, how much more reasonably may I complain if you form, without consideration, such an estimate of myself as is contradicted by your own experience! You would not therefore go so far astray in your judgment as to believe, when you had written nothing by which I could be offended, that I would nevertheless be so foolish as to be capable of being offended by such a reply.
Source: Letters (New Advent)