Summa Theologica, Part I (Prima Pars) From the Complete...

Objection 1: It would seem that the angels do not know material things. For the object understood is the perfection of him who understands it. But material things cannot be the perfections of angels, since they are beneath them. Therefore the angels do not know material things.

Obj. 2: Further, intellectual vision is only of such things as exist within the soul by their essence, as is said in the gloss [*On 2 Cor. 12:2, taken from Augustine (Gen. ad lit. xii. 28)]. But the material things cannot enter by their essence into man's soul, nor into the angel's mind. Therefore they cannot be known by intellectual vision, but only by imaginary vision, whereby the images of bodies are apprehended, and by sensible vision, which regards bodies in themselves. Now there is neither imaginary nor sensible vision in the angels, but only intellectual. Therefore the angels cannot know material things.

I answer that, The established order of things is for the higher beings to be more perfect than the lower; and for whatever is contained deficiently, partially, and in manifold manner in the lower beings, to be contained in the higher eminently, and in a certain degree of fulness and simplicity. Therefore, in God, as in the highest source of things, all things pre-exist supersubstantially in respect of His simple Being itself, as Dionysius says (Div. Nom. 1). But among other creatures the angels are nearest to God, and resemble Him most; hence they share more fully and more perfectly in the Divine goodness, as Dionysius says (Coel. Hier. iv). Consequently, all material things pre-exist in the angels more simply and less materially even than in themselves, yet in a more manifold manner and less perfectly than in God.

Now whatever exists in any subject, is contained in it after the manner of such subject. But the angels are intellectual beings of their own nature. Therefore, as God knows material things by His essence, so do the angels know them, forasmuch as they are in the angels by their intelligible species.

Reply Obj. 1: The thing understood is the perfection of the one who understands, by reason of the intelligible species which he has in his intellect. And thus the intelligible species which are in the intellect of an angel are perfections and acts in regard to that intellect.

Reply Obj. 2: Sense does not apprehend the essences of things, but only their outward accidents. In like manner neither does the imagination; for it apprehends only the images of bodies. The intellect alone apprehends the essences of things. Hence it is said (De Anima iii, text. 26) that the object of the intellect is "what a thing is," regarding which it does not err; as neither does sense regarding its proper sensible object. So therefore the essences of material things are in the intellect of man and angels, as the thing understood is in him who understands, and not according to their real natures. But some things are in an intellect or in the soul according to both natures; and in either case there is intellectual vision.

Reply Obj. 3: If an angel were to draw his knowledge of material things from the material things themselves, he would require to make them actually intelligible by a process of abstraction. But he does not derive his knowledge of them from the material things themselves; he has knowledge of material things by actually intelligible species of things, which species are connatural to him; just as our intellect has, by species which it makes intelligible by abstraction. _______________________

Objection 1: It would seem that angels do not know singulars. For the Philosopher says (Poster. i, text. 22): "The sense has for its object singulars, but the intellect, universals." Now, in the angels there is no power of understanding save the intellectual power, as is evident from what was said above (Q. 54, A. 5). Consequently they do not know singulars.

Obj. 2: Further, all knowledge comes about by some assimilation of the knower to the object known. But it is not possible for any assimilation to exist between an angel and a singular object, in so far as it is singular; because, as was observed above (Q. 50, A. 2), an angel is immaterial, while matter is the principle of singularity. Therefore the angel cannot know singulars.

Obj. 3: Further, if an angel does know singulars, it is either by singular or by universal species. It is not by singular species; because in this way he would require to have an infinite number of species. Nor is it by universal species; since the universal is not the sufficient principle for knowing the singular as such, because singular things are not known in the universal except potentially. Therefore the angel does not know singulars.

I answer that, Some have denied to the angels all knowledge of singulars. In the first place this derogates from the Catholic faith, which asserts that these lower things are administered by angels, according to Heb. 1:14: "They are all ministering spirits." Now, if they had no knowledge of singulars, they could exercise no provision over what is going on in this world; since acts belong to individuals: and this is against the text of Eccles. 5:5: "Say not before the angel: There is no providence." Secondly, it is also contrary to the teachings of philosophy, according to which the angels are stated to be the movers of the heavenly spheres, and to move them according to their knowledge and will.

Consequently others have said that the angel possesses knowledge of singulars, but in their universal causes, to which all particular effects are reduced; as if the astronomer were to foretell a coming eclipse from the dispositions of the movements of the heavens. This opinion does not escape the aforesaid implications; because, to know a singular, merely in its universal causes, is not to know it as singular, that is, as it exists here and now. The astronomer, knowing from computation of the heavenly movements that an eclipse is about to happen, knows it in the universal; yet he does not know it as taking place now, except by the senses. But administration, providence and movement are of singulars, as they are here and now existing.

Therefore, it must be said differently, that, as man by his various powers of knowledge knows all classes of things, apprehending universals and immaterial things by his intellect, and things singular and corporeal by the senses, so an angel knows both by his one mental power. For the order of things runs in this way, that the higher a thing is, so much the more is its power united and far-reaching: thus in man himself it is manifest that the common sense which is higher than the proper sense, although it is but one faculty, knows everything apprehended by the five outward senses, and some other things which no outer sense knows; for example, the difference between white and sweet. The same is to be observed in other cases. Accordingly, since an angel is above man in the order of nature, it is unreasonable to say that a man knows by any one of his powers something which an angel by his one faculty of knowledge, namely, the intellect, does not know. Hence Aristotle pronounces it ridiculous to say that a discord, which is known to us, should be unknown to God (De Anima i, text. 80; Metaph. text. 15).

The manner in which an angel knows singular things can be considered from this, that, as things proceed from God in order that they may subsist in their own natures, so likewise they proceed in order that they may exist in the angelic mind. Now it is clear that there comes forth from God not only whatever belongs to their universal nature, but likewise all that goes to make up their principles of individuation; since He is the cause of the entire substance of the thing, as to both its matter and its form. And for as much as He causes, does He know; for His knowledge is the cause of a thing, as was shown above (Q. 14, A. 8). Therefore as by His essence, by which He causes all things, God is the likeness of all things, and knows all things, not only as to their universal natures, but also as to their singularity; so through the species imparted to them do the angels know things, not only as to their universal nature, but likewise in their individual conditions, in so far as they are the manifold representations of that one simple essence.

Reply Obj. 1: The Philosopher is speaking of our intellect, which apprehends only by a process of abstraction; and by such abstraction from material conditions the thing abstracted becomes a universal. Such a manner of understanding is not in keeping with the nature of the angels, as was said above (Q. 55, A. 2, A. 3 ad 1), and consequently there is no comparison.

Reply Obj. 2: It is not according to their nature that the angels are likened to material things, as one thing resembles another by agreement in genus, species, or accident; but as the higher bears resemblance to the lower, as the sun does to fire. Even in this way there is in God a resemblance of all things, as to both matter and form, in so far as there pre-exists in Him as in its cause whatever is to be found in things. For the same reason, the species in the angel's intellect, which are images drawn from the Divine essence, are the images of things not only as to their form, but also as to their matter.

Reply Obj. 3: Angels know singulars by universal forms, which nevertheless are the images of things both as to their universal, and as to their individuating principles. How many things can be known by the same species, has been already stated above (Q. 55, A. 3, ad 3). _______________________

Obj. 2: Further, the present and the future are differences of time. But the angel's intellect is above time; because, as is said in De Causis, "an intelligence keeps pace with eternity," that is, aeviternity. Therefore, to the angel's mind, past and future are not different, but he knows each indifferently.

Obj. 3: Further, the angel does not understand by species derived from things, but by innate universal species. But universal species refer equally to present, past, and future. Therefore it appears that the angels know indifferently things past, present, and future.

On the contrary, Whatever is the exclusive sign of the Divinity, does not belong to the angels. But to know future events is the exclusive sign of the Divinity, according to Isa. 41:23: "Show the things that are to come hereafter, and we shall know that ye are gods." Therefore the angels do not know future events.

I answer that, The future can be known in two ways. First, it can be known in its cause. And thus, future events which proceed necessarily from their causes, are known with sure knowledge; as that the sun will rise tomorrow. But events which proceed from their causes in the majority of cases, are not known for certain, but conjecturally; thus the doctor knows beforehand the health of the patient. This manner of knowing future events exists in the angels, and by so much the more than it does in us, as they understand the causes of things both more universally and more perfectly; thus doctors who penetrate more deeply into the causes of an ailment can pronounce a surer verdict on the future issue thereof. But events which proceed from their causes in the minority of cases are quite unknown; such as casual and chance events.

In another way future events are known in themselves. To know the future in this way belongs to God alone; and not merely to know those events which happen of necessity, or in the majority of cases, but even casual and chance events; for God sees all things in His eternity, which, being simple, is present to all time, and embraces all time. And therefore God's one glance is cast over all things which happen in all time as present before Him; and He beholds all things as they are in themselves, as was said before when dealing with God's knowledge (Q. 14, A. 13). But the mind of an angel, and every created intellect, fall far short of God's eternity; hence the future as it is in itself cannot be known by any created intellect.