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Fathers of the Church

Letter XI


”Augustine’s correspondence, the mark and expression of the influential personality and apostolic zeal of the author, is rich in historical, philosophical, theological, exegetical, spiritual, literary, and autobiographical content” (Agostino Trapè). Here he responds to a question raised by his friend Nebridius concerning the mystery of the Incarnation.


The correspondence of St. Augustine that has been preserved includes more than 270 letters, including well over 200 written by him. Those numbered 1-30 span the period between his conversion and his episcopal ordination.

by Augustine of Hippo in 389 | translated by J. G. Cunningham


1. When the question, which has long been brought before me by you with something even of friendly chiding, as to the way in which we might live together, was seriously disturbing my mind, and I had resolved to write to you, and to beg an answer from you bearing exclusively on this subject, and to employ my pen on no other theme pertaining to our studies, in order that the discussion of this matter between us might be brought to an end, the very short and indisputable conclusion stated in your letter lately received at once delivered me from all further solicitude; your statement being to the effect that on this matter there ought to be no further deliberation, because as soon as it is in my power to come to you, or in your power to come to me, we shall feel alike constrained to improve the opportunity. My mind being thus, as I have said, at rest, I looked over all your letters, that I. might see what yet remained unanswered. In these I have found so many questions, that even if they were easily solved, they would by their mere number more than exhaust the time and talents of any man. But they are so difficult, that if the answering of even one of them were laid upon me, I would not hesitate to confess myself heavily burdened. The design of this introductory statement is to make you desist for a little from asking new questions until I am free from debt, and that you confine yourself in your answer to the statement of your opinion of my replies. At the same time, I know that it is to my own loss that I postpone for even a little while the participation of your divine thoughts.

2. Hear, therefore, the view which I hold concerning the mystery of the Incarnation which the religion wherein we have been instructed commends to our faith and knowledge as having been accomplished in order to our salvation; which question I have chosen to discuss in preference to all the rest, although it is not the most easily answered. For those questions which are proposed by you concerning this world do not appear to me to have a sufficiently direct reference to the obtaining of a happy life; and whatever pleasure they yield when investigated, there is reason to fear lest they take up time which ought to be devoted to better things. With regard, then, to the subject which I have at this time undertaken, first of all I am surprised that you were perplexed by the question why not the Father, but the Son, is said to have become incarnate, and yet were not also perplexed by the same question in regard to the Holy Spirit. For the union of Persons in the Trinity is in the Catholic faith set forth and believed, and by a few holy and blessed ones understood, to be so inseparable, that whatever is done by the Trinity must be regarded as being done by the Father, and by the Son, and by the Holy Spirit together; and that nothing is done by the Father which is not also done by the Son and by the Holy Spirit; and nothing done by the Holy Spirit which is not also done by the Father and by the Son; and nothing done by the Son which is not also done by the Father and by the Holy Spirit. From which it seems to follow as a consequence, that the whole Trinity assumed human nature; for if the Son did so, but the Father and the Spirit did not, there is something in which they act separately. Why, then, in our mysteries and sacred symbols, is the Incarnation ascribed only to the Son? This is a very great question, So difficult, and on a subject so vast, that it is impossible either to give a sufficiently clear statement, or to support it by satisfactory proofs. I venture, however, since I am writing to you, to indicate rather than explain what my sentiments are, in order that you, from your talents and our intimacy, through which you thoroughly know me, may for yourself fill up the outline.

3. There is no nature, Nebridius—and, indeed, there is no substance—which does not contain in itself and exhibit these three things: first, that it is; next, that it is this or that; and third, that as far as possible it remains as it is. The first of these three presents the original cause of nature from which all things exist; the second presents the form according to which all things are fashioned and formed in a particular way; the third presents a certain permanence, so to speak, in which all things are. Now, if it be possible that a thing can be, and yet not be this or that, and not remain in its own generic form; or that a thing can be this or that, and yet not be, and not remain in its own generic form, so far as it is possible for it to do so; or that a thing can remain in its own generic form according to the force belonging to it, and yet not be, and not be this or that,—then it is also possible that in that Trinity one Person can do something in which the others have no part. But if you see that whatever is must forthwith be this or that, and must remain so far as possible in its own generic form, you see also that these Three do nothing in which all have not a part. I see that as yet I have only treated a portion of this question, which makes its solution difficult. But I wished to open up briefly to you—if, indeed, I have succeeded in this—how great in the system of Catholic truth is the doctrine of the inseparability of the Persons of the Trinity, and how difficult to be understood.

4. Hear now how that which disquiets your mind may disquiet it no more. The mode of existence (Species—the second of the three above named) which is properly ascribed to the Son, has to do with training, and with a certain art, if I may use that word in regard to such things, and with the exercise of intellect, by which the mind itself is moulded in its thoughts upon things. Therefore, since by that assumption of human nature the work accomplished was the effective presentation to us of a certain training in the right way of living, and exemplification of that which is commanded, under the majesty and perspicuousness of certain sentences, it is not without reason that all this is ascribed to the Son. For in many things which I leave your own reflection and prudence to suggest, although the constituent elements be many, some one nevertheless stands out above the rest, and therefore not unreasonably claims a right of possession, as it were, of the whole for itself: as, e.g., in the. three kinds of questions above mentioned, although the question raised be whether a thing is or not, this involves necessarily also both what it is (this or that), for of course it cannot be at all unless it be something, and whether it ought to be approved of or disapproved of, for whatever is is a fit subject for some opinion as to its quality; in like manner, when the question raised is what a thing is, this necessarily involves both that it is, and that its quality may be tried by some standard; and in the same way, when the question raised is what is the quality of a thing, this necessarily involves that that thing is, and is something, since all things are inseparably joined to themselves; nevertheless, the question in each of the above cases takes its name not from all the three, but from the special point towards which the inquirer directed his attention. Now there is a certain training necessary for men, by which they might be instructed and formed after some model. We cannot say, however, regarding that which is accomplished in men by this training, either that it does not exist, or that it is not a thing to be desired [i.e. we cannot say what it is, without involving an affirmation both of its existence and of its quality]; but we seek first to know what it is, for in knowing this we know that by which we may infer that it is something, and in which we may remain. Therefore the first thing necessary was, that a certain rule and pattern of training be plainly exhibited; and this was done by the divinely appointed method of the Incarnation, which is properly to be ascribed to the Son, in order that from it should follow both our knowledge, through the Son, of the Father Himself, i.e. of the one first principle whence all things have their being, and a certain inward and ineffable charm and sweetness of remaining in that knowledge, and of despising all mortal things,—a gift and work which is properly ascribed to the Holy Spirit. Wherefore, although in all things the Divine Persons act perfectly in common, and without possibility of separation, nevertheless their operations behoved to be exhibited in such a way as to be distinguished from each other, on account of the weakness which is in us, who have fallen from unity into variety. For no one ever succeeds in raising another to the height on which he himself stands, unless he stoop somewhat towards the level which that other occupies.

You have here a letter which may not indeed put an end to your disquietude in regard to this doctrine, but which may set your own thoughts to work upon a kind of solid foundation; so that, with the talents which I well know you to possess, you may follow, and, by the piety in which especially we must be stedfast, may apprehend that which still remains to be discovered.

Taken from "The Early Church Fathers and Other Works" originally published by Wm. B. Eerdmans Pub. Co. in English in Edinburgh, Scotland, beginning in 1867. (NPNF I/I, Schaff). The digital version is by The Electronic Bible Society, P.O. Box 701356, Dallas, TX 75370, 214-407-WORD.