Thomas Aquinas, Summa Theologiae

Objection 1: It would seem that the angels know all things by their substance. For Dionysius says (Div. Nom. vii) that "the angels, according to the proper nature of a mind, know the things which are happening upon earth." But the angel's nature is his essence. Therefore the angel knows things by his essence.

Objection 2: Further, according to the Philosopher (Metaph. xii, text. 51; De Anima iii, text. 15), "in things which are without matter, the intellect is the same as the object understood." But the object understood is the same as the one who understands it, as regards that whereby it is understood. Therefore in things without matter, such as the angels, the medium whereby the object is understood is the very substance of the one understanding it.

Objection 3: Further, everything which is contained in another is there according to the mode of the container. But an angel has an intellectual nature. Therefore whatever is in him is there in an intelligible mode. But all things are in him: because the lower orders of beings are essentially in the higher, while the higher are in the lower participatively: and therefore Dionysius says (Div. Nom. iv) that God "enfolds the whole in the whole," i.e. all in all. Therefore the angel knows all things in his substance.

On the contrary, Dionysius says (Div. Nom. iv) that "the angels are enlightened by the forms of things." Therefore they know by the forms of things, and not by their own substance.

I answer that, The medium through which the intellect understands, is compared to the intellect understanding it as its form, because it is by the form that the agent acts. Now in order that the faculty may be perfectly completed by the form, it is necessary for all things to which the faculty extends to be contained under the form. Hence it is that in things which are corruptible, the form does not perfectly complete the potentiality of the matter: because the potentiality of the matter extends to more things than are contained under this or that form. But the intellective power of the angel extends to understanding all things: because the object of the intellect is universal being or universal truth. The angel's essence, however, does not comprise all things in itself, since it is an essence restricted to a genus and species. This is proper to the Divine essence, which is infinite, simply and perfectly to comprise all things in Itself. Therefore God alone knows all things by His essence. But an angel cannot know all things by his essence; and his intellect must be perfected by some species in order to know things.

Reply to Objection 1: When it is said that the angel knows things according to his own nature, the words "according to" do not determine the medium of such knowledge, since the medium is the similitude of the thing known; but they denote the knowing power, which belongs to the angel of his own nature.

Reply to Objection 2: As the sense in act is the sensible in act, as stated in De Anima ii, text. 53, not so that the sensitive power is the sensible object's likeness contained in the sense, but because one thing is made from both as from act and potentiality: so likewise the intellect in act is said to be the thing understood in act, not that the substance of the intellect is itself the similitude by which it understands, but because that similitude is its form. Now, it is precisely the same thing to say "in things which are without matter, the intellect is the same thing as the object understood," as to say that "the intellect in act is the thing understood in act"; for a thing is actually understood, precisely because it is immaterial.

Reply to Objection 3: The things which are beneath the angel, and those which are above him, are in a measure in his substance, not indeed perfectly, nor according to their own proper formality---because the angel's essence, as being finite, is distinguished by its own formality from other things---but according to some common formality. Yet all things are perfectly and according to their own formality in God's essence, as in the first and universal operative power, from which proceeds whatever is proper or common to anything. Therefore God has a proper knowledge of all things by His own essence: and this the angel has not, but only a common knowledge.

Articulus 1

Argumentum 1

Ad primum sic proceditur. Videtur quod Angeli cognoscant omnia per suam substantiam.

Dicit enim dionysius, VII cap. De div. Nom., quod Angeli sciunt ea quae sunt in terra, secundum propriam naturam mentis.

Sed natura Angeli est eius essentia.

Ergo Angelus per suam essentiam res cognoscit.

Argumentum 2

Praeterea, secundum philosophum, in XII metaphys., et in III de anima, in his quae sunt sine materia, idem est intellectus et quod intelligitur.

Id autem quod intelligitur est idem intelligenti ratione eius quo intelligitur. Ergo in his quae sunt sine materia, sicut sunt Angeli, id quo intelligitur est ipsa substantia intelligentis.

Argumentum 3

Praeterea, omne quod est in altero, est in eo per modum eius in quo est. Sed Angelus habet naturam intellectualem. Ergo quidquid est in ipso, est in eo per modum intelligibilem. Sed omnia sunt in eo, quia inferiora in entibus sunt in superioribus essentialiter, superiora vero sunt in inferioribus participative; et ideo dicit dionysius, IV cap. De div. Nom., quod deus tota in totis congregat, idest omnia in omnibus.

Ergo Angelus omnia in sua substantia cognoscit.

Sed Contra

Sed contra est quod dionysius dicit, in eodem capite, quod Angeli illuminantur rationibus rerum. Ergo cognoscunt per rationes rerum, et non per propriam substantiam.

Corpus

Respondeo dicendum quod illud quo intellectus intelligit, comparatur ad intellectum intelligentem ut forma eius, quia forma est quo agens agit. Oportet autem, ad hoc quod potentia perfecte compleatur per formam, quod omnia contineantur sub forma, ad quae potentia se extendit. Et inde est quod in rebus corruptibilibus forma non perfecte complet potentiam materiae, quia potentia materiae ad plura se extendit quam sit continentia formae huius vel illius. Potentia autem intellectiva Angeli se extendit ad intelligendum omnia, quia obiectum intellectus est ens vel verum commune. Ipsa autem essentia Angeli non comprehendit in se omnia, cum sit essentia determinata ad genus et ad speciem.

Hoc autem proprium est essentiae divinae, quae infinita est, ut in se simpliciter omnia comprehendat perfecte. Et ideo solus deus cognoscit omnia per suam essentiam. Angelus autem per suam essentiam non potest omnia cognoscere; sed oportet intellectum eius aliquibus speciebus perfici ad res cognoscendas.

Ad 1

Ad primum ergo dicendum quod, cum dicitur Angelum secundum suam naturam res cognoscere, ly secundum non determinat medium cognitionis, quod est similitudo cogniti; sed virtutem cognoscitivam, quae convenit Angelo secundum suam naturam.

Ad 2

Ad secundum dicendum quod, sicut sensus in actu est sensibile in actu, ut dicitur in III de anima, non ita quod ipsa vis sensitiva sit ipsa similitudo sensibilis quae est in sensu, sed quia ex utroque fit unum sicut ex actu et potentia; ita et intellectus in actu dicitur esse intellectum in actu, non quod substantia intellectus sit ipsa similitudo per quam intelligit, sed quia illa similitudo est forma eius. Idem est autem quod dicitur, in his quae sunt sine materia, idem est intellectus et quod intelligitur, ac si diceretur quod intellectus in actu est intellectum in actu, ex hoc enim aliquid est intellectum in actu quod est immateriale.

Ad 3

Ad tertium dicendum quod ea quae sunt infra Angelum, et ea quae sunt supra ipsum, sunt quodammodo in substantia eius, non quidem perfecte, neque secundum propriam rationem, cum Angeli essentia, finita existens, secundum propriam rationem ab aliis distinguatur; sed secundum quandam rationem communem. In essentia autem dei sunt omnia perfecte et secundum propriam rationem, sicut in prima et universali virtute operativa, a qua procedit quidquid est in quacumque re vel proprium vel commune.

Et ideo deus per essentiam suam habet propriam cognitionem de rebus omnibus, non autem Angelus, sed solam communem.