Letter 12: Augustine gives Nebridius a compact answer on the incarnation of the Son.

You write that you have sent more letters than we have received. I cannot refuse to believe you, but I cannot distrust myself either. Even if I cannot match you in answering, I do keep your letters with no less care than you send them. We both agree that you have received no more than two of my longer letters, because I have not sent a third. When I checked my copies, I noticed that I had answered about five of your questions. One of them, however, was touched only in passing. I was not reckless in leaving it to your intelligence, but perhaps that brief treatment did not satisfy your hunger for understanding. You need to restrain that hunger a little and accept some shortcuts gladly. Of course, if I cheat your understanding by being too sparing with words, then spare me nothing. You have every right to demand the full debt from me, and nothing could be more welcome, if only I had the strength to pay it in full. Count this letter, then, among my shorter ones. I would not let it take nothing from my heap of obligations to you; after all, you send shorter letters too, and they do not make that heap any smaller. As for your question about the Son of God, why he rather than the Father is said to have assumed a human being, though both act together, you will grasp it easily if you remember our conversations, where we tried as best we could to speak of what the Son of God is, by whom we are joined to God. The matter is beyond speech, but I will touch it briefly here. The very discipline and form of God, through whom all things that have been made were made, is called the Son. Whatever was done through the human nature he assumed was done for our teaching and formation.

EPISTOLA 12 Scripta inter a. 389 et a. 391. A. quaestionem de Incarnatione in superiore epistola perstrictam iterum tractandam suscipit (Epistolae minima pars nobis pervenit). Nebridio Augustinus 1. Plures epistolas te scribis misisse quam accepimus; sed neque tibi possum non credere, neque mihi tu. Etsi enim rescribendo par esse non valeo; tamen non minore a me diligentia servantur litterae tuae, quam frequentantur abs te. Prolixiores autem nostras, non te amplius quam binas accepisse convenit inter nos; non enim misimus tertias. Sane recognitis exemplaribus animadverti quinque fere tuis rogationibus esse responsum; nisi quod una ibi quaestio quasi transeunter perstricta, quanquam non temere ingenio tuo commissa sit, non tamen fortasse satisfecit avaritiae tuae; quam refrenes aliquantulum opus est, et nonnulla compendia libenter feras. Ita plane ut si quidquam fraudo intelligentiam, dum sum parcus in verbis, nihil parcas mihi; sed tu iure, quo mihi valentius esset forte aliquid, si quidquam posset esse iucundius, totum quod debetur, efflagites. Hanc igitur epistolam numerabis inter minores epistolas meas, quam tibi non sivi nihil mihi de acervo minuere. Non enim et tu mittis minores, quae non eumdem acervum augeant. Quare illud quod de Filio Dei quaeris, cur ipse potius dicatur hominem suscepisse, quam Pater, cum simul uterque sit, dignosces facillime si sermocinationum nostrarum quibus, ut potuimus (nam ineffabile quiddam est), quid sit Dei Filius quo coniuncti simus, recorderis. Quod ut hic breviter attingam, disciplina ipsa et forma Dei, per quam facta sunt omnia quae facta sunt, Filius nuncupatur. Quidquid autem per susceptum illum hominem gestum est, ad eruditionem informationemque nostram gestum est.