1 Objection 1: It seems that the act of God's intellect is not His substance. For to understand is an operation. But an operation signifies something proceeding from the operator. Therefore the act of God's intellect is not His substance.
1 Ad quartum sic proceditur. Videtur quod ipsum intelligere Dei non sit eius substantia. Intelligere enim est quaedam operatio. Operatio autem aliquid significat procedens ab operante. Ergo ipsum intelligere Dei non est ipsa Dei substantia.
2 Objection 2: Further, to understand one's act of understanding, is to understand something that is neither great nor chiefly understood, and but secondary and accessory. If therefore God be his own act of understanding, His act of understanding will be as when we understand our act of understanding: and thus God's act of understanding will not be something great.
2 Praeterea, cum aliquis intelligit se intelligere, hoc non est intelligere aliquid magnum vel principale intellectum, sed intelligere quoddam secundarium et accessorium. Si igitur Deus sit ipsum intelligere, intelligere Deum erit sicut cum intelligimus intelligere. Et sic non erit aliquid magnum intelligere Deum.
3 Objection 3: Further, every act of understanding means understanding something. When therefore God understands Himself, if He Himself is not distinct from this act of understanding, He understands that He understands Himself; and so on to infinity. Therefore the act of God's intellect is not His substance.
3 Praeterea, omne intelligere est aliquid intelligere. Cum ergo Deus intelligit se, si ipsemet non est aliud quam suum intelligere, intelligit se intelligere, et intelligere se intelligere se, et sic in infinitum. Non ergo ipsum intelligere Dei est eius substantia.
4 On the contrary, Augustine says De Trin. vii), In God to be is the same as to be wise. But to be wise is the same thing as to understand. Therefore in God to be is the same thing as to understand. But God's existence is His substance, as shown above Question 3, Article 4). Therefore the act of God's intellect is His substance.
4 Sed contra est quod dicit Augustinus, Lib. VII de Trin., Deo hoc est esse, quod sapientem esse. Hoc autem est sapientem esse, quod intelligere. Ergo Deo hoc est esse, quod intelligere. Sed esse Dei est eius substantia, ut supra ostensum est. Ergo intelligere Dei est eius substantia.
5 I answer that, It must be said that the act of God's intellect is His substance. For if His act of understanding were other than His substance, then something else, as the Philosopher says Metaph. xii), would be the act and perfection of the divine substance, to which the divine substance would be related, as potentiality is to act, which is altogether impossible; because the act of understanding is the perfection and act of the one understanding. Let us now consider how this is. As was laid down above Article 2), to understand is not an act passing to anything extrinsic; for it remains in the operator as his own act and perfection; as existence is the perfection of the one existing: just as existence follows on the form, so in like manner to understand follows on the intelligible species. Now in God there is no form which is something other than His existence, as shown above Question 3). Hence as His essence itself is also His intelligible species, it necessarily follows that His act of understanding must be His essence and His existence. Thus it follows from all the foregoing that in God, intellect, and the object understood, and the intelligible species, and His act of understanding are entirely one and the same. Hence when God is said to be understanding, no kind of multiplicity is attached to His substance.
5 Respondeo dicendum quod est necesse dicere quod intelligere Dei est eius substantia. Nam si intelligere Dei sit aliud quam eius substantia, oporteret, ut dicit philosophus in XII Metaphys., quod aliquid aliud esset actus et perfectio substantiae divinae, ad quod se haberet substantia divina sicut potentia ad actum quod est omnino impossibile), nam intelligere est perfectio et actus intelligentis. Hoc autem qualiter sit, considerandum est. Sicut enim supra dictum est, intelligere non est actio progrediens ad aliquid extrinsecum, sed manet in operante sicut actus et perfectio eius, prout esse est perfectio existentis, sicut enim esse consequitur formam, ita intelligere sequitur speciem intelligibilem. In Deo autem non est forma quae sit aliud quam suum esse, ut supra ostensum est. Unde, cum ipsa sua essentia sit etiam species intelligibilis, ut dictum est, ex necessitate sequitur quod ipsum eius intelligere sit eius essentia et eius esse. Et sic patet ex omnibus praemissis quod in Deo intellectus, et id quod intelligitur, et species intelligibilis, et ipsum intelligere, sunt omnino unum et idem. Unde patet quod per hoc quod Deus dicitur intelligens, nulla multiplicitas ponitur in eius substantia.
6 Reply to Objection 1: To understand is not an operation proceeding out of the operator, but remaining in him.
6 Ad primum ergo dicendum quod intelligere non est operatio exiens ab ipso operante, sed manens in ipso.
7 Reply to Objection 2: When that act of understanding which is not subsistent is understood, something not great is understood; as when we understand our act of understanding; and so this cannot be likened to the act of the divine understanding which is subsistent. Thus appears the Reply to the Third Objection. For the act of divine understanding subsists in itself, and belongs to its very self and is not another's; hence it need not proceed to infinity.
7 Ad secundum dicendum quod, cum intelligitur illud intelligere quod non est subsistens, non intelligitur aliquid magnum; sicut cum intelligimus intelligere nostrum. Et ideo non est simile de ipso intelligere divino, quod est subsistens. Et per hoc patet responsio ad tertium. Nam intelligere divinum, quod est in seipso subsistens, est sui ipsius; et non alicuius alterius, ut sic oporteat procedere in infinitum.