Thomas Aquinas, Summa Theologiae

Objection 1: It would seem that the trinity of the divine persons can be known by natural reason. For philosophers came to the knowledge of God not otherwise than by natural reason. Now we find that they said many things about the trinity of persons, for Aristotle says (De Coelo et Mundo i, 2): "Through this number"---namely, three---"we bring ourselves to acknowledge the greatness of one God, surpassing all things created." And Augustine says (Confess. vii, 9): "I have read in their works, not in so many words, but enforced by many and various reasons, that in the beginning was the Word, and the Word was with God, and the Word was God," and so on; in which passage the distinction of persons is laid down. We read, moreover, in a gloss on Rm. 1 and Ex. 8 that the magicians of Pharaoh failed in the third sign---that is, as regards knowledge of a third person---i.e. of the Holy Ghost ---and thus it is clear that they knew at least two persons. Likewise Trismegistus says: "The monad begot a monad, and reflected upon itself its own heat." By which words the generation of the Son and procession of the Holy Ghost seem to be indicated. Therefore knowledge of the divine persons can be obtained by natural reason.

Objection 2: Further, Richard St. Victor says (De Trin. i, 4): "I believe without doubt that probable and even necessary arguments can be found for any explanation of the truth." So even to prove the Trinity some have brought forward a reason from the infinite goodness of God, who communicates Himself infinitely in the procession of the divine persons; while some are moved by the consideration that "no good thing can be joyfully possessed without partnership." Augustine proceeds (De Trin. x, 4; x, 11,12) to prove the trinity of persons by the procession of the word and of love in our own mind; and we have followed him in this (Question 27, Articles 1,3). Therefore the trinity of persons can be known by natural reason.

Objection 3: Further, it seems to be superfluous to teach what cannot be known by natural reason. But it ought not to be said that the divine tradition of the Trinity is superfluous. Therefore the trinity of persons can be known by natural reason.

On the contrary, Hilary says (De Trin. i), "Let no man think to reach the sacred mystery of generation by his own mind." And Ambrose says (De Fide ii, 5), "It is impossible to know the secret of generation. The mind fails, the voice is silent." But the trinity of the divine persons is distinguished by origin of generation and procession (Question 30, Article 2). Since, therefore, man cannot know, and with his understanding grasp that for which no necessary reason can be given, it follows that the trinity of persons cannot be known by reason.

I answer that, It is impossible to attain to the knowledge of the Trinity by natural reason. For, as above explained (Question 12, Articles 4,12), man cannot obtain the knowledge of God by natural reason except from creatures. Now creatures lead us to the knowledge of God, as effects do to their cause. Accordingly, by natural reason we can know of God that only which of necessity belongs to Him as the principle of things, and we have cited this fundamental principle in treating of God as above (Question 12, Article 12). Now, the creative power of God is common to the whole Trinity; and hence it belongs to the unity of the essence, and not to the distinction of the persons. Therefore, by natural reason we can know what belongs to the unity of the essence, but not what belongs to the distinction of the persons. Whoever, then, tries to prove the trinity of persons by natural reason, derogates from faith in two ways. Firstly, as regards the dignity of faith itself, which consists in its being concerned with invisible things, that exceed human reason; wherefore the Apostle says that "faith is of things that appear not" (Heb. 11:1), and the same Apostle says also, "We speak wisdom among the perfect, but not the wisdom of this world, nor of the princes of this world; but we speak the wisdom of God in a mystery which is hidden" (1 Cor. 2:6,7). Secondly, as regards the utility of drawing others to the faith. For when anyone in the endeavor to prove the faith brings forward reasons which are not cogent, he falls under the ridicule of the unbelievers: since they suppose that we stand upon such reasons, and that we believe on such grounds.

Therefore, we must not attempt to prove what is of faith, except by authority alone, to those who receive the authority; while as regards others it suffices to prove that what faith teaches is not impossible. Hence it is said by Dionysius (Div. Nom. ii): "Whoever wholly resists the word, is far off from our philosophy; whereas if he regards the truth of the word"---i.e. "the sacred word, we too follow this rule."

Reply to Objection 1: The philosophers did not know the mystery of the trinity of the divine persons by its proper attributes, such as paternity, filiation, and procession, according to the Apostle's words, "We speak the wisdom of God which none of the princes of the world"---i.e. the philosophers---"knew" (1 Cor. 2:6). Nevertheless, they knew some of the essential attributes appropriated to the persons, as power to the Father, wisdom to the Son, goodness to the Holy Ghost; as will later on appear. So, when Aristotle said, "By this number," etc., we must not take it as if he affirmed a threefold number in God, but that he wished to say that the ancients used the threefold number in their sacrifices and prayers on account of some perfection residing in the number three. In the Platonic books also we find, "In the beginning was the word," not as meaning the Person begotten in God, but as meaning the ideal type whereby God made all things, and which is appropriated to the Son. And although they knew these were appropriated to the three persons, yet they are said to have failed in the third sign---that is, in the knowledge of the third person, because they deviated from the goodness appropriated to the Holy Ghost, in that knowing God "they did not glorify Him as God" (Rm. 1); or, because the Platonists asserted the existence of one Primal Being whom they also declared to be the father of the universe, they consequently maintained the existence of another substance beneath him, which they called "mind" or the "paternal intellect," containing the idea of all things, as Macrobius relates (Som. Scip. iv). They did not, however, assert the existence of a third separate substance which might correspond to the Holy Ghost. So also we do not assert that the Father and the Son differ in substance, which was the error of Origen and Arius, who in this followed the Platonists. When Trismegistus says, "Monad begot monad," etc., this does not refer to the generation of the Son, or to the procession of the Holy Ghost, but to the production of the world. For one God produced one world by reason of His love for Himself.

Reply to Objection 2: Reason may be employed in two ways to establish a point: firstly, for the purpose of furnishing sufficient proof of some principle, as in natural science, where sufficient proof can be brought to show that the movement of the heavens is always of uniform velocity. Reason is employed in another way, not as furnishing a sufficient proof of a principle, but as confirming an already established principle, by showing the congruity of its results, as in astrology the theory of eccentrics and epicycles is considered as established, because thereby the sensible appearances of the heavenly movements can be explained; not, however, as if this proof were sufficient, forasmuch as some other theory might explain them. In the first way, we can prove that God is one; and the like. In the second way, reasons avail to prove the Trinity; as, when assumed to be true, such reasons confirm it. We must not, however, think that the trinity of persons is adequately proved by such reasons. This becomes evident when we consider each point; for the infinite goodness of God is manifested also in creation, because to produce from nothing is an act of infinite power. For if God communicates Himself by His infinite goodness, it is not necessary that an infinite effect should proceed from God: but that according to its own mode and capacity it should receive the divine goodness. Likewise, when it is said that joyous possession of good requires partnership, this holds in the case of one not having perfect goodness: hence it needs to share some other's good, in order to have the goodness of complete happiness. Nor is the image in our mind an adequate proof in the case of God, forasmuch as the intellect is not in God and ourselves univocally. Hence, Augustine says (Tract. xxvii. in Joan.) that by faith we arrive at knowledge, and not conversely.

Reply to Objection 3: There are two reason why the knowledge of the divine persons was necessary for us. It was necessary for the right idea of creation. The fact of saying that God made all things by His Word excludes the error of those who say that God produced things by necessity. When we say that in Him there is a procession of love, we show that God produced creatures not because He needed them, nor because of any other extrinsic reason, but on account of the love of His own goodness. So Moses, when he had said, "In the beginning God created heaven and earth," subjoined, "God said, Let there be light," to manifest the divine Word; and then said, "God saw the light that it was good," to show proof of the divine love. The same is also found in the other works of creation. In another way, and chiefly, that we may think rightly concerning the salvation of the human race, accomplished by the Incarnate Son, and by the gift of the Holy Ghost.

Articulus 1

Argumentum 1

Ad primum sic proceditur. Videtur quod trinitas divinarum personarum possit per naturalem rationem cognosci. Philosophi enim non devenerunt in dei cognitionem nisi per rationem naturalem, inveniuntur autem a philosophis multa dicta de trinitate personarum.

Dicit enim Aristoteles, in I de caelo et mundo, per hunc numerum, scilicet ternarium, adhibuimus nos ipsos magnificare deum unum, eminentem proprietatibus eorum quae sunt creata.

Augustinus etiam dicit, VII confes., ibi legi, scilicet in libris Platonicorum, non quidem his verbis, sed hoc idem omnino, multis et multiplicibus suaderi rationibus, quod in principio erat verbum, et verbum erat apud deum, et deus erat verbum, et huiusmodi quae ibi sequuntur, in quibus verbis distinctio divinarum personarum traditur. Dicitur etiam in Glossa Rom. I, et Exod. VIII, quod magi Pharaonis defecerunt in tertio signo, idest in notitia tertiae personae, scilicet spiritus sancti, et sic ad minus duas cognoverunt.

Trismegistus etiam dixit, monas genuit monadem, et in se suum reflexit ardorem, per quod videtur generatio filii, et spiritus sancti processio intimari. Cognitio ergo divinarum personarum potest per rationem naturalem haberi.

Argumentum 2

Praeterea, Ricardus de sancto victore dicit, in libro de Trin., credo sine dubio quod ad quamcumque explanationem veritatis, non modo probabilia, imo etiam necessaria argumenta non desint.

Unde etiam ad probandum trinitatem personarum, aliqui induxerunt rationem ex infinitate bonitatis divinae, quae seipsam infinite communicat in processione divinarum personarum.

Quidam vero per hoc, quod nullius boni sine consortio potest esse iucunda possessio.

Augustinus vero procedit ad manifestandum trinitatem personarum, ex processione verbi et amoris in mente nostra, quam viam supra secuti sumus.

Ergo per rationem naturalem potest cognosci trinitas personarum.

Argumentum 3

Praeterea, superfluum videtur homini tradere quod humana ratione cognosci non potest. Sed non est dicendum quod traditio divina de cognitione trinitatis sit superflua. Ergo trinitas personarum ratione humana cognosci potest.

Sed Contra

Sed contra est quod Hilarius dicit, in libro II de Trin., non putet homo sua intelligentia generationis sacramentum posse consequi.

Ambrosius etiam dicit, impossibile est generationis scire secretum, mens deficit, vox silet.

Sed per originem generationis et processionis distinguitur trinitas in personis divinis, ut ex supra dictis patet.

Cum ergo illud homo non possit scire et intelligentia consequi, ad quod ratio necessaria haberi non potest, sequitur quod trinitas personarum per rationem cognosci non possit.

Corpus

Respondeo dicendum quod impossibile est per rationem naturalem ad cognitionem trinitatis divinarum personarum pervenire.

Ostensum est enim supra quod homo per rationem naturalem in cognitionem dei pervenire non potest nisi ex creaturis.

Creaturae autem ducunt in dei cognitionem, sicut effectus in causam. Hoc igitur solum ratione naturali de deo cognosci potest, quod competere ei necesse est secundum quod est omnium entium principium, et hoc fundamento usi sumus supra in consideratione dei.

Virtus autem creativa dei est communis toti trinitati, unde pertinet ad unitatem essentiae, non ad distinctionem personarum.

Per rationem igitur naturalem cognosci possunt de deo ea quae pertinent ad unitatem essentiae, non autem ea quae pertinent ad distinctionem personarum. Qui autem probare nititur trinitatem personarum naturali ratione, fidei dupliciter derogat.

Primo quidem, quantum ad dignitatem ipsius fidei, quae est ut sit de rebus invisibilibus, quae rationem humanam excedunt.

Unde apostolus dicit, ad Heb. XI, quod fides est de non apparentibus. Et apostolus dicit, I Cor. II, sapientiam loquimur inter perfectos, sapientiam vero non huius saeculi, neque principum huius saeculi; sed loquimur dei sapientiam in mysterio, quae abscondita est.

Secundo, quantum ad utilitatem trahendi alios ad fidem. Cum enim aliquis ad probandam fidem inducit rationes quae non sunt cogentes, cedit in irrisionem infidelium, credunt enim quod huiusmodi rationibus innitamur, et propter eas credamus. Quae igitur fidei sunt, non sunt tentanda probare nisi per auctoritates, his qui auctoritates suscipiunt. Apud alios vero, sufficit defendere non esse impossibile quod praedicat fides.

Unde dionysius dicit, II cap. De div. Nom., si aliquis est qui totaliter eloquiis resistit, longe erit a nostra philosophia; si autem ad veritatem eloquiorum, scilicet sacrorum, respicit, hoc et nos canone utimur.

Ad 1

Ad primum ergo dicendum quod philosophi non cognoverunt mysterium trinitatis divinarum personarum per propria, quae sunt paternitas, filiatio et processio; secundum illud apostoli, I ad Cor. II, loquimur dei sapientiam, quam nemo principum huius saeculi cognovit, idest philosophorum, secundum Glossam.

Cognoverunt tamen quaedam essentialia attributa quae appropriantur personis, sicut potentia patri, sapientia filio, bonitas spiritui sancto, ut infra patebit.

Quod ergo Aristoteles dicit, per hunc numerum adhibuimus nos ipsos etc., non est sic intelligendum, quod ipse poneret ternarium numerum in divinis, sed vult dicere quod antiqui utebantur ternario numero in sacrificiis et orationibus, propter quandam ternarii numeri perfectionem.

In libris etiam Platonicorum invenitur in principio erat verum, non secundum quod verbum significat personam genitam in divinis, sed secundum quod per verbum intelligitur ratio idealis, per quam deus omnia condidit, quae filio appropriatur.

Et licet appropriata tribus personis cognoscerent, dicuntur tamen in tertio signo defecisse, idest in cognitione tertiae personae, quia a bonitate, quae spiritui sancto appropriatur, deviaverunt, dum cognoscentes deum, non sicut deum glorificaverunt, ut dicitur Rom. I.

Vel, quia ponebant Platonici unum primum ens, quod etiam dicebant esse patrem totius universitatis rerum, consequenter ponebant aliam substantiam sub eo, quam vocabant mentem vel paternum intellectum, in qua erant rationes omnium rerum, sicut Macrobius recitat super somnium scipionis, non autem ponebant aliquam substantiam tertiam separatam, quae videretur spiritui sancto respondere.

Sic autem nos non ponimus patrem et filium, secundum substantiam differentes, sed hoc fuit error Origenis et Arii.

Sequentium in hoc Platonicos. Quod vero trismegistus dixit, monas monadem genuit, et in se suum reflexit ardorem, non est referendum ad generationem filii vel processionem spiritus sancti, sed ad productionem mundi, nam unus deus produxit unum mundum propter sui ipsius amorem.

Ad 2

Ad secundum dicendum quod ad aliquam rem dupliciter inducitur ratio. Uno modo, ad probandum sufficienter aliquam radicem, sicut in scientia naturali inducitur ratio sufficiens ad probandum quod motus caeli semper sit uniformis velocitatis. Alio modo inducitur ratio, non quae sufficienter probet radicem, sed quae radici iam positae ostendat congruere consequentes effectus, sicut in astrologia ponitur ratio excentricorum et epicyclorum ex hoc quod, hac positione facta, possunt salvari apparentia sensibilia circa motus caelestes, non tamen ratio haec est sufficienter probans, quia etiam forte alia positione facta salvari possent. Primo ergo modo potest induci ratio ad probandum deum esse unum, et similia. Sed secundo modo se habet ratio quae inducitur ad manifestationem trinitatis, quia scilicet, trinitate posita, congruunt huiusmodi rationes; non tamen ita quod per has rationes sufficienter probetur trinitas personarum. Et hoc patet per singula. Bonitas enim infinita dei manifestatur etiam in productione creaturarum, quia infinitae virtutis est ex nihilo producere. Non enim oportet, si infinita bonitate se communicat, quod aliquid infinitum a deo procedat, sed secundum modum suum recipiat divinam bonitatem.

Similiter etiam quod dicitur, quod sine consortio non potest esse iucunda possessio alicuius boni, locum habet quando in una persona non invenitur perfecta bonitas; unde indiget, ad plenam iucunditatis bonitatem, bono alicuius alterius consociati sibi. Similitudo autem intellectus nostri non sufficienter probat aliquid de deo, propter hoc quod intellectus non univoce invenitur in deo et in nobis.

Et inde est quod Augustinus, super Ioan., dicit quod per fidem venitur ad cognitionem, et non e converso.

Ad 3

Ad tertium dicendum quod cognitio divinarum personarum fuit necessaria nobis dupliciter. Uno modo, ad recte sentiendum de creatione rerum. Per hoc enim quod dicimus deum omnia fecisse verbo suo, excluditur error ponentium deum produxisse res ex necessitate naturae.

Per hoc autem quod ponimus in eo processionem amoris, ostenditur quod deus non propter aliquam indigentiam creaturas produxit, neque propter aliquam aliam causam extrinsecam; sed propter amorem suae bonitatis.

Unde et Moyses, postquam dixerat, in principio creavit deus caelum et terram, subdit, dixit deus, fiat lux, ad manifestationem divini verbi; et postea dixit, vidit deus lucem, quod esset bona, ad ostendendum approbationem divini amoris; et similiter in aliis operibus.

Alio modo, et principalius, ad recte sentiendum de salute generis humani, quae perficitur per filium incarnatum, et per donum spiritus sancti.