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

Objection 1: It would seem that the demons' intellect is darkened by being deprived of the knowledge of all truth. For if they knew any truth at all, they would most of all know themselves; which is to know separated substances. But this is not in keeping with their unhappiness: for this seems to belong to great happiness, insomuch as that some writers have assigned as man's last happiness the knowledge of the separated substances. Therefore the demons are deprived of all knowledge of truth.

Obj. 2: Further, what is most manifest in its nature, seems to be specially manifest to the angels, whether good or bad. That the same is not manifest with regard to ourselves, comes from the weakness of our intellect which draws its knowledge from phantasms; as it comes from the weakness of its eye that the owl cannot behold the light of the sun. But the demons cannot know God, Who is most manifest of Himself, because He is the sovereign truth; and this is because they are not clean of heart, whereby alone can God be seen. Therefore neither can they know other things.

Obj. 3: Further, according to Augustine (Gen. ad lit. iv, 22), the proper knowledge of the angels is twofold; namely, morning and evening. But the demons have no morning knowledge, because they do not see things in the Word; nor have they the evening knowledge, because this evening knowledge refers the things known to the Creator's praise (hence, after "evening" comes "morning" [Gen. 1]). Therefore the demons can have no knowledge of things.

Obj. 4: Further, the angels at their creation knew the mystery of the kingdom of God, as Augustine says (Gen. ad lit. v, 19; De Civ. Dei xi). But the demons are deprived of such knowledge: "for if they had known it, they would never have crucified the Lord of glory," as is said 1 Cor. 2:8. Therefore, for the same reason, they are deprived of all other knowledge of truth.

Obj. 5: Further, whatever truth anyone knows is known either naturally, as we know first principles; or by deriving it from someone else, as we know by learning; or by long experience, as the things we learn by discovery. Now, the demons cannot know the truth by their own nature, because, as Augustine says (De Civ. Dei xi, 33), the good angels are separated from them as light is from darkness; and every manifestation is made through light, as is said Eph. 5:13. In like manner they cannot learn by revelation, nor by learning from the good angels: because "there is no fellowship of light with darkness [*Vulg.: 'What fellowship hath . . . ?']" (2 Cor. 6:14). Nor can they learn by long experience: because experience comes of the senses. Consequently there is no knowledge of truth in them.

On the contrary, Dionysius says (Div. Nom. iv) that, "certain gifts were bestowed upon the demons which, we say, have not been changed at all, but remain entire and most brilliant." Now, the knowledge of truth stands among those natural gifts. Consequently there is some knowledge of truth in them.

I answer that, The knowledge of truth is twofold: one which comes of nature, and one which comes of grace. The knowledge which comes of grace is likewise twofold: the first is purely speculative, as when Divine secrets are imparted to an individual; the other is effective, and produces love for God; which knowledge properly belongs to the gift of wisdom.

Of these three kinds of knowledge the first was neither taken away nor lessened in the demons. For it follows from the very nature of the angel, who, according to his nature, is an intellect or mind: since on account of the simplicity of his substance, nothing can be withdrawn from his nature, so as to punish him by subtracting from his natural powers, as a man is punished by being deprived of a hand or a foot or of something else. Therefore Dionysius says (Div. Nom. iv) that the natural gifts remain entire in them. Consequently their natural knowledge was not diminished. The second kind of knowledge, however, which comes of grace, and consists in speculation, has not been utterly taken away from them, but lessened; because, of these Divine secrets only so much is revealed to them as is necessary; and that is done either by means of the angels, or "through some temporal workings of Divine power," as Augustine says (De Civ. Dei ix, 21); but not in the same degree as to the holy angels, to whom many more things are revealed, and more fully, in the Word Himself. But of the third knowledge, as likewise of charity, they are utterly deprived.

Reply Obj. 1: Happiness consists in self-application to something higher. The separated substances are above us in the order of nature; hence man can have happiness of a kind by knowing the separated substances, although his perfect happiness consists in knowing the first substance, namely, God. But it is quite natural for one separate substance to know another; as it is natural for us to know sensible natures. Hence, as man's happiness does not consist in knowing sensible natures; so neither does the angel's happiness consist in knowing separated substances.

Reply Obj. 2: What is most manifest in its nature is hidden from us by its surpassing the bounds of our intellect; and not merely because our intellect draws knowledge from phantasms. Now the Divine substance surpasses the proportion not only of the human intellect, but even of the angelic. Consequently, not even an angel can of his own nature know God's substance. Yet on account of the perfection of his intellect he can of his nature have a higher knowledge of God than man can have. Such knowledge of God remains also in the demons. Although they do not possess the purity which comes with grace, nevertheless they have purity of nature; and this suffices for the knowledge of God which belongs to them from their nature.

Reply Obj. 3: The creature is darkness in comparison with the excellence of the Divine light; and therefore the creature's knowledge in its own nature is called "evening" knowledge. For the evening is akin to darkness, yet it possesses some light: but when the light fails utterly, then it is night. So then the knowledge of things in their own nature, when referred to the praise of the Creator, as it is in the good angels, has something of the Divine light, and can be called evening knowledge; but if it be not referred to God, as is the case with the demons, it is not called evening, but "nocturnal" knowledge. Accordingly we read in Gen. 1:5 that the darkness, which God separated from the light, "He called night."

Reply Obj. 4: All the angels had some knowledge from the very beginning respecting the mystery of God's kingdom, which found its completion in Christ; and most of all from the moment when they were beatified by the vision of the Word, which vision the demons never had. Yet all the angels did not fully and equally apprehend it; hence the demons much less fully understood the mystery of the Incarnation, when Christ was in the world. For, as Augustine observes (De Civ. Dei ix, 21), "It was not manifested to them as it was to the holy angels, who enjoy a participated eternity of the Word; but it was made known by some temporal effects, so as to strike terror into them." For had they fully and certainly known that He was the Son of God and the effect of His passion, they would never have procured the crucifixion of the Lord of glory.

Reply Obj. 5: The demons know a truth in three ways: first of all by the subtlety of their nature; for although they are darkened by privation of the light of grace, yet they are enlightened by the light of their intellectual nature: secondly, by revelation from the holy angels; for while not agreeing with them in conformity of will, they do agree, nevertheless, by their likeness of intellectual nature, according to which they can accept what is manifested by others: thirdly, they know by long experience; not as deriving it from the senses; but when the similitude of their innate intelligible species is completed in individual things, they know some things as present, which they previously did not know would come to pass, as we said when dealing with the knowledge of the angels (Q. 57, A. 3, ad 3). _______________________

Objection 1: It would seem that the will of the demons is not obstinate in evil. For liberty of will belongs to the nature of an intellectual being, which nature remains in the demons, as we said above (A. 1). But liberty of will is directly and firstly ordained to good rather than to evil. Therefore the demons' will is not so obstinate in evil as not to be able to return to what is good.

Obj. 2: Further, since God's mercy is infinite, it is greater than the demons' malice, which is finite. But no one returns from the malice of sin to the goodness of justice save through God's mercy. Therefore the demons can likewise return from their state of malice to the state of justice.

Obj. 3: Further, if the demons have a will obstinate in evil, then their will would be especially obstinate in the sin whereby they fell. But that sin, namely, pride, is in them no longer; because the motive for the sin no longer endures, namely, excellence. Therefore the demon is not obstinate in malice.

Obj. 4: Further, Gregory says (Moral. iv) that man can be reinstated by another, since he fell through another. But, as was observed already (Q. 63, A. 8), the lower demons fell through the highest one. Therefore their fall can be repaired by another. Consequently they are not obstinate in malice.

Obj. 5: Further, whoever is obstinate in malice, never performs any good work. But the demon performs some good works: for he confesses the truth, saying to Christ: "I know Who Thou art, the holy one of God" (Mark 1:24). "The demons" also "believe and tremble" (James 2:19). And Dionysius observes (Div. Nom. iv), that "they desire what is good and best, which is, to be, to live, to understand." Therefore they are not obstinate in malice.

I answer that, It was Origen's opinion [*Peri Archon i. 6] that every will of the creature can by reason of free-will be inclined to good and evil; with the exception of the soul of Christ on account of the union of the Word. Such a statement deprives angels and saints of true beatitude, because everlasting stability is of the very nature of true beatitude; hence it is termed "life everlasting." It is also contrary to the authority of Sacred Scripture, which declares that demons and wicked men shall be sent "into everlasting punishment," and the good brought "into everlasting life." Consequently such an opinion must be considered erroneous; while according to Catholic Faith, it must be held firmly both that the will of the good angels is confirmed in good, and that the will of the demons is obstinate in evil.

We must seek for the cause of this obstinacy, not in the gravity of the sin, but in the condition of their nature or state. For as Damascene says (De Fide Orth. ii), "death is to men, what the fall is to the angels." Now it is clear that all the mortal sins of men, grave or less grave, are pardonable before death; whereas after death they are without remission and endure for ever.

To find the cause, then, of this obstinacy, it must be borne in mind that the appetitive power is in all things proportioned to the apprehensive, whereby it is moved, as the movable by its mover. For the sensitive appetite seeks a particular good; while the will seeks the universal good, as was said above (Q. 59, A. 1); as also the sense apprehends particular objects, while the intellect considers universals. Now the angel's apprehension differs from man's in this respect, that the angel by his intellect apprehends immovably, as we apprehend immovably first principles which are the object of the habit of "intelligence"; whereas man by his reason apprehends movably, passing from one consideration to another; and having the way open by which he may proceed to either of two opposites. Consequently man's will adheres to a thing movably, and with the power of forsaking it and of clinging to the opposite; whereas the angel's will adheres fixedly and immovably. Therefore, if his will be considered before its adhesion, it can freely adhere either to this or to its opposite (namely, in such things as he does not will naturally); but after he has once adhered, he clings immovably. So it is customary to say that man's free-will is flexible to the opposite both before and after choice; but the angel's free-will is flexible either opposite before the choice, but not after. Therefore the good angels who adhered to justice, were confirmed therein; whereas the wicked ones, sinning, are obstinate in sin.

Reply Obj. 3: The devil's first sin still remains in him according to desire; although not as to his believing that he can obtain what he desired. Even so, if a man were to believe that he can commit murder, and wills to commit it, and afterwards the power is taken from him; nevertheless, the will to murder can stay with him, so that he would he had done it, or still would do it if he could.

Reply Obj. 5: A demon's act is twofold. One comes of deliberate will; and this is properly called his own act. Such an act on the demon's part is always wicked; because, although at times he does something good, yet he does not do it well; as when he tells the truth in order to deceive; and when he believes and confesses, yet not willingly, but compelled by the evidence of things. Another kind of act is natural to the demon; this can be good and bears witness to the goodness of nature. Yet he abuses even such good acts to evil purpose. _______________________