Thomas Aquinas, Summa Theologiae

Objection 1: It seems that God is not supremely "one." For "one" is so called from the privation of division. But privation cannot be greater or less. Therefore God is not more "one" than other things which are called "one."

Objection 2: Further, nothing seems to be more indivisible than what is actually and potentially indivisible; such as a point and unity. But a thing is said to be more "one" according as it is indivisible. Therefore God is not more "one" than unity is "one" and a point is "one."

Objection 3: Further, what is essentially good is supremely good. Therefore what is essentially "one" is supremely "one." But every being is essentially "one," as the Philosopher says (Metaph. iv). Therefore every being is supremely "one"; and therefore God is not "one" more than any other being is "one."

On the contrary, Bernard says (De Consid. v): "Among all things called one, the unity of the Divine Trinity holds the first place."

I answer that, Since "one" is an undivided being, if anything is supremely "one" it must be supremely being, and supremely undivided. Now both of these belong to God. For He is supremely being, inasmuch as His being is not determined by any nature to which it is adjoined; since He is being itself, subsistent, absolutely undetermined. But He is supremely undivided inasmuch as He is divided neither actually nor potentially, by any mode of division; since He is altogether simple, as was shown above (Question 3, Article 7). Hence it is manifest that God is "one" in the supreme degree.

Reply to Objection 1: Although privation considered in itself is not susceptive of more or less, still according as its opposite is subject to more or less, privation also can be considered itself in the light of more and less. Therefore according as a thing is more divided, or is divisible, either less or not at all, in the degree it is called more, or less, or supremely, "one."

Reply to Objection 2: A point and unity which is the principle of number, are not supremely being, inasmuch as they have being only in some subject. Hence neither of them can be supremely "one." For as a subject cannot be supremely "one," because of the difference within it of accident and subject, so neither can an accident.

Reply to Objection 3: Although every being is "one" by its substance, still every such substance is not equally the cause of unity; for the substance of some things is compound and of others simple.

Articulus 4

Argumentum 1

Ad quartum sic proceditur. Videtur quod deus non sit maxime unus. Unum enim dicitur secundum privationem divisionis. Sed privatio non recipit magis et minus. Ergo deus non dicitur magis unus quam alia quae sunt unum.

Argumentum 2

Praeterea, nihil videtur esse magis indivisibile quam id quod est indivisibile actu et potentia, cuiusmodi est punctus et unitas.

Sed intantum dicitur aliquid magis unum, inquantum est indivisibile. Ergo deus non est magis unum quam unitas et punctus.

Argumentum 3

Praeterea, quod est per essentiam bonum, est maxime bonum, ergo quod est per essentiam suam unum, est maxime unum.

Sed omne ens est unum per suam essentiam, ut patet per philosophum in IV metaphys..

Ergo omne ens est maxime unum.

Deus igitur non est magis unum quam alia entia.

Sed Contra

Sed contra est quod dicit bernardus, quod inter omnia quae unum dicuntur, arcem tenet unitas divinae trinitatis.

Corpus

Respondeo dicendum quod, cum unum sit ens indivisum, ad hoc quod aliquid sit maxime unum, oportet quod sit et maxime ens et maxime indivisum. Utrumque autem competit deo. Est enim maxime ens, inquantum est non habens aliquod esse determinatum per aliquam naturam cui adveniat, sed est ipsum esse subsistens, omnibus modis indeterminatum. Est autem maxime indivisum, inquantum neque dividitur actu neque potentia, secundum quemcunque modum divisionis, cum sit omnibus modis simplex, ut supra ostensum est.

Unde manifestum est quod deus est maxime unus.

Ad 1

Ad primum ergo dicendum quod, licet privatio secundum se non recipiat magis et minus, tamen secundum quod eius oppositum recipit magis et minus, etiam ipsa privativa dicuntur secundum magis et minus. Secundum igitur quod aliquid est magis divisum vel divisibile, vel minus, vel nullo modo, secundum hoc aliquid dicitur magis et minus vel maxime unum.

Ad 2

Ad secundum dicendum quod punctus et unitas quae est principium numeri, non sunt maxime entia, cum non habeant esse nisi in subiecto aliquo. Unde neutrum eorum est maxime unum. Sicut enim subiectum non est maxime unum, propter diversitatem accidentis et subiecti, ita nec accidens.

Ad 3

Ad tertium dicendum quod, licet omne ens sit unum per suam substantiam, non tamen se habet aequaliter substantia cuiuslibet ad causandam unitatem, quia substantia quorundam est ex multis composita, quorundam vero non.