Augustine, On the Trinity 1.5 [my italics].
Let me ask of my reader,
wherever, alike with myself, he is certain, there to go on with me;
wherever, alike with myself, he hesitates, there to join with me in inquiring;
wherever he recognizes himself to be in error, there to return to me;
wherever he recognizes me to be so, there to call me back: so that we may enter together upon the path of charity, and advance towards Him of whom it is said, Seek His face evermore.
And I would make this pious and safe agreement, in the presence of our Lord God, with all who read my writings, as well in all other cases as, above all, in the case of those which inquire into the unity of the Trinity, of the Father and the Son and the Holy Spirit; because in no other subject is error more dangerous, or inquiry more laborious, or the discovery of truth more profitable.
If, then, any reader shall say, This is not well said, because I do not understand it; such an one finds fault with my language, not with my faith: and it might perhaps in very truth have been put more clearly; yet no man ever so spoke as to be understood in all things by all men.
Let him, therefore, who finds this fault with my discourse, see whether he can understand other men who have handled similar subjects and questions, when he does not understand me: and if he can, let him put down my book, or even, if he pleases, throw it away; and let him spend labor and time rather on those whom he understands.
Yet let him not think on that account that I ought to have been silent, because I have not been able to express myself so smoothly and clearly to him as those do whom he understands. For neither do all things, which all men have written, come into the hands of all. And possibly some, who are capable of understanding even these our writings, may not find those more lucid works, and may meet with ours only.
And therefore it is useful that many persons should write many books, differing in style but not in faith, concerning even the same questions, that the matter itself may reach the greatest number — some in one way, some in another.
But if he who complains that he has not understood these things has never been able to comprehend any careful and exact reasonings at all upon such subjects, let him in that case deal with himself by resolution and study, that he may know better; not with me by quarrellings and wranglings, that I may hold my peace.
Let him, again, who says, when he reads my book, Certainly I understand what is said, but it is not true, assert, if he pleases, his own opinion, and refute mine if he is able. And if he do this with charity and truth, and take the pains to make it known to me (if I am still alive), I shall then receive the most abundant fruit of this my labor. And if he cannot inform myself, most willing and glad should I be that he should inform those whom he can.
Yet, for my part, I meditate in the law of the Lord, if not day and night, at least such short times as I can; and I commit my meditations to writing, lest they should escape me through forgetfulness; hoping by the mercy of God that He will make me hold steadfastly all truths of which I feel certain; but if in anything I be otherwise minded, that He will himself reveal even this to me, whether through secret inspiration and admonition, or through His own plain utterances, or through the reasonings of my brethren. This I pray for, and this my trust and desire I commit to Him, who is sufficiently able to keep those things which He has given me, and to render those which He has promised.