Letter 240: Pascentius challenges Augustine on how three divine persons can be one God.

Pascentius to Augustine. I had hoped, dearest brother, that you would put aside the counsel of your former error. Now I am astonished that you still remain in it, as the letter you sent me cries out. Your Dignity is like a man inflamed with excessive heat and thirst: if he finds muddy water and gulps it down, then even if he later finds clear cold water and drinks it, it cannot do him much good, because his heart and soul have already once been buried in mud. In short, if you will permit me to say so, the counsel of Your Excellency is like a crooked, knotty tree that has nothing straight in it and distorts the line of sight. Your Holiness writes back to me: the Father is God, the Son is God, the Holy Spirit is God, and yet there is one God. Which one of the three is the one God? Or is there perhaps one three-formed person who is called by this name? If you had wished, and if you had confidence in your profession, you would sit down with me and your fellow bishops with a pure and peaceful mind and spirit, and you would discuss the things of God and the matters that concern spiritual glory and grace. So what need is there to write and write back in a way that does not build us up?

EPISTOLA 240 Scripta versus a. 404. Pascentius Augustino contumeliose illum compellans urgensque ut proferat quis e tribus divinis Personis sit unus Deus, ad conflictum sub arbitris provocans. AUGUSTINO PASCENTIUS 1. Optaveram te, frater dilectissime, pristini erroris tui consilium deponere; nunc miror te in ipso adhuc permanere, sicut epistola quam ad me misisti, clamat. Nam ita est Dignatio tua, sicut sitiens nimio calore accensus, si invenerit aquam caenosam et se inde ingurgitaverit; postea, etiamsi limpidam et frigidam reperiens biberit, non satis proficere potest, quandoquidem caeno semel eius cor et anima obruitur. Denique, quod pace tua dicam, ita est consilium Praestantiae tuae, sicut arbor / curva et nodosa, quae nihil in se rectum habet, et aciem pervertit oculorum. Rescribit mihi Sanctitas tua Patrem Deum, Filium Deum, Spiritum Sanctum Deum, sed unum Deum. Quis e tribus unus Deus? an forte est una persona triformis, quae hoc nomine nuncupetur? Tu si voluisses et confideres de professione tua, resideres mecum cum coepiscopis tuis puro ac pacifico animo et spiritu, et conferres de iis quae sunt Dei, et quae ad gloriam et gratiam spiritalem pertinent. Unde, quid opus est scribere et rescribere quod nos non aedificat?