Thomas Aquinas, Summa Theologiae

Objection 1: It would seem that we can understand many things at the same time. For intellect is above time, whereas the succession of before and after belongs to time. Therefore the intellect does not understand different things in succession, but at the same time.

Objection 2: Further, there is nothing to prevent different forms not opposed to each other from actually being in the same subject, as, for instance, color and smell are in the apple. But intelligible species are not opposed to each other. Therefore there is nothing to prevent the same intellect being in act as regards different intelligible species, and thus it can understand many things at the same time.

Objection 3: Further, the intellect understands a whole at the same time, such as a man or a house. But a whole contains many parts. Therefore the intellect understands many things at the same time.

Objection 4: Further, we cannot know the difference between two things unless we know both at the same time (De Anima iii, 2), and the same is to be said of any other comparison. But our intellect knows the difference and comparison between one thing and another. Therefore it knows many things at the same time.

On the contrary, It is said (Topic. ii, 10) that "understanding is of one thing only, knowledge is of many."

I answer that, The intellect can, indeed, understand many things as one, but not as many: that is to say by "one" but not by "many" intelligible species. For the mode of every action follows the form which is the principle of that action. Therefore whatever things the intellect can understand under one species, it can understand at the same time: hence it is that God sees all things at the same time, because He sees all in one, that is, in His Essence. But whatever things the intellect understands under different species, it does not understand at the same time. The reason of this is that it is impossible for one and the same subject to be perfected at the same time by many forms of one genus and diverse species, just as it is impossible for one and the same body at the same time to have different colors or different shapes. Now all intelligible species belong to one genus, because they are the perfections of one intellectual faculty: although the things which the species represent belong to different genera. Therefore it is impossible for one and the same intellect to be perfected at the same time by different intelligible species so as actually to understand different things.

Reply to Objection 1: The intellect is above that time, which is the measure of the movement of corporeal things. But the multitude itself of intelligible species causes a certain vicissitude of intelligible operations, according as one operation succeeds another. And this vicissitude is called time by Augustine, who says (Gen. ad lit. viii, 20,22), that "God moves the spiritual creature through time."

Reply to Objection 2: Not only is it impossible for opposite forms to exist at the same time in the same subject, but neither can any forms belonging to the same genus, although they be not opposed to one another, as is clear from the examples of colors and shapes.

Reply to Objection 3: Parts can be understood in two ways. First, in a confused way, as existing in the whole, and thus they are known through the one form of the whole, and so are known together. In another way they are known distinctly: thus each is known by its species; and so they are not understood at the same time.

Reply to Objection 4: If the intellect sees the difference or comparison between one thing and another, it knows both in relation to their difference or comparison; just, as we have said above (ad 3), as it knows the parts in the whole.

Articulus 4

Argumentum 1

Ad quartum sic proceditur. Videtur quod possimus multa simul intelligere. Intellectus enim est supra tempus. Sed prius et posterius ad tempus pertinent. Ergo intellectus non intelligit diversa secundum prius et posterius, sed simul.

Argumentum 2

Praeterea, nihil prohibet diversas formas non oppositas simul eidem actu inesse, sicut odorem et colorem pomo. Sed species intelligibiles non sunt oppositae. Ergo nihil prohibet intellectum unum simul fieri in actu secundum diversas species intelligibiles et sic potest multa simul intelligere.

Argumentum 3

Praeterea, intellectus simul intelligit aliquod totum, ut hominem vel domum. Sed in quolibet toto continentur multae partes.

Ergo intellectus simul multa intelligit.

Argumentum 4

Praeterea, non potest cognosci differentia unius ad alterum, nisi simul utrumque apprehendatur, ut dicitur in libro de anima, et eadem ratio est de quacumque alia comparatione. Sed intellectus noster cognoscit differentiam et comparationem unius ad alterum.

Ergo cognoscit multa simul.

Sed Contra

Sed contra est quod dicitur in libro topic., quod intelligere est unum solum, scire vero multa.

Corpus

Respondeo dicendum quod intellectus quidem potest multa intelligere per modum unius, non autem multa per modum multorum, dico autem per modum unius vel multorum, per unam vel plures species intelligibiles. Nam modus cuiusque actionis consequitur formam quae est actionis principium. Quaecumque ergo intellectus potest intelligere sub una specie, simul intelligere potest, et inde est quod deus omnia simul videt, quia omnia videt per unum, quod est essentia sua. Quaecumque vero intellectus per diversas species intelligit, non simul intelligit. Et huius ratio est, quia impossibile est idem subiectum perfici simul pluribus formis unius generis et diversarum specierum, sicut impossibile est quod idem corpus secundum idem simul coloretur diversis coloribus, vel figuretur diversis figuris. Omnes autem species intelligibiles sunt unius generis, quia sunt perfectiones unius intellectivae potentiae; licet res quarum sunt species, sint diversorum generum. Impossibile est ergo quod idem intellectus simul perficiatur diversis speciebus intelligibilibus, ad intelligendum diversa in actu.

Ad 1

Ad primum ergo dicendum quod intellectus est supra tempus quod est numerus motus corporalium rerum. Sed ipsa pluralitas specierum intelligibilium causat vicissitudinem quandam intelligibilium operationum, secundum quam una operatio est prior altera.

Et hanc vicissitudinem Augustinus nominat tempus, cum dicit, VIII super Gen. Ad litt., quod deus movet creaturam spiritualem per tempus.

Ad 2

Ad secundum dicendum quod non solum oppositae formae non possunt esse simul in eodem subiecto, sed nec quaecumque formae eiusdem generis, licet non sint oppositae, sicut patet per exemplum inductum de coloribus et figuris.

Ad 3

Ad tertium dicendum quod partes possunt intelligi dupliciter.

Uno modo, sub quadam confusione, prout sunt in toto, et sic cognoscuntur per unam formam totius, et sic simul cognoscuntur. Alio modo, cognitione distincta, secundum quod quaelibet cognoscitur per suam speciem, et sic non simul intelliguntur.

Ad 4

Ad quartum dicendum quod quando intellectus intelligit differentiam vel comparationem unius ad alterum, cognoscit utrumque differentium vel comparatorum sub ratione ipsius comparationis vel differentiae; sicut dictum est quod cognoscit partes sub ratione totius.