8 I had written some time ago a letter to you on this subject, which was not delivered to you, because the bearer to whom it was entrusted did not finish his journey to you. From it I may quote a thought which occurred to me while I was dictating it, and which I ought not to omit in this letter, in order that, if your opinion is still different from mine, and is better, you may readily forgive the anxiety which has moved me to write. It is this: If your opinion is different, and is according to truth (for only in that case can it be better than mine), you will grant that “a mistake of mine, which is in the interest of truth, cannot deserve great blame, if indeed it deserves blame at all, when it is possible for you to use truth in the interest of falsehood without doing wrong.”
9. As to the reply which you were pleased to give me concerning Origen, I did not need to be told that we should, not only in ecclesiastical writers, but in all others, approve and commend what we find right and true, but reject and condemn what we find false and mischievous. What I craved from your wisdom and learning (and I still crave it), was that you should acquaint us definitely with the points in which that remarkable man is proved to have departed from the belief of the truth. Moreover, in that book in which you have mentioned all the ecclesiastical writers whom you could remember, and their works, it would, I think, be a more convenient arrangement if, after naming those whom you know to be heretics (since you have chosen not to pass them without notice), you would add in what respect their doctrine is to be avoided. Some of these heretics also you have omitted, and I would fain know on what grounds. If, however, perchance it has been from a desire not to enlarge that volume unduly that you refrained from adding to a notice of heretics, the statement of the things in which the Catholic Church has authoritatively condemned them, I beg you not to grudge bestowing on this subject, to which with humility and brotherly love I direct your attention, a portion of that literary labour by which already, by the grace of the Lord our God, you have in no small measure stimulated and assisted the saints in the study of the Latin tongue, and publish in one small book (if your other occupations permit you) a digest of the perverse dogmas of all the heretics who up to this time have, through arrogance, or ignorance, or self-will, attempted to subvert the simplicity of the Christian faith; a work most necessary for the information of those who are prevented, either by lack of leisure or by their not knowing the Greek language, from reading and understanding so many things. I would urge my request at greater length, were it not that this is commonly a sign of misgivings as to the benevolence of the party from whom a favour is sought. Meanwhile I cordially recommend to your goodwill in Christ our brother Paulus, to whose high standing in these regions I bear before God willing testimony.
Source: Letters (New Advent)