Article 17 — Whether the soul, when separated from the body, can understand separate substances

Seventeenth, it is asked whether the soul, when separated from the body, can understand separate substances. (Parallel texts: ST I.89.2; SCG III.45; Quodlibet III, q. 9, a. 1.)

Obj. 1: It seems that it cannot. For a more perfect operation is characteristic of a more perfect substance. (Cf. John Damascene, On the Orthodox Faith, bk. 2, ch. 23 (PG 94:950–51); SCG II.91.) Now the soul is more perfect when united to the body than when existing apart from it. This is evident because every part of a whole is more perfect when united to the whole than when separated from it.

Therefore, if the soul is unable to understand separate substances when it is actually joined to the body, it seems that the soul cannot understand these substances when it exists apart from the body. (Cf. ST I.89.2, obj. 1.)

Obj. 2: Further, our soul can know separate substances either by its nature or by grace alone. If it knows them by its own nature, then, since it is natural to the soul to be united to the body, the soul is not prevented from knowing separate substances by being united to the body. However, if the soul knows them by grace alone, it follows that at least not all separated souls know separate substances, for not all souls existing apart from bodies possess grace.

Obj. 3: Further, the soul is united to the body in order that the soul may be perfected therein by the sciences and the virtues. However, the greatest perfection of the soul consists in knowing separate substances. (Cf. Averroes, Commentary on Aristotle’s On the Soul, bk. 3, comm. 36.) Therefore, if the soul understands separate substances in virtue of its separation alone, then the soul is united to the body unnecessarily.

Obj. 4: Further, if the soul, when separated from the body, knows a separate substance, it must know such a substance either through that substance’s essence, or through a species of it. But the soul does not know a separate substance through its essence, because the essence of a separate substance is not the same as that of a separated soul. Similarly, the soul cannot know a separate substance through a species of such a substance, for no species can be abstracted by the soul from separate substances, because they are simple. (Gennadius of Marseilles, Book of Ecclesiastical Dogmas, ch. 50 (PL 42:1221); ch. 83 (PL 58:999B); cf. Aquinas, On Truth, q. 8, a. 7, obj. 4.) Consequently, when the soul exists apart from the body, it can in no way know separate substances. (Cf. ST I.89.2, obj. 2.)

Obj. 5: Further, if the soul, existing in separation from the body, knows a separate substance, the soul apprehends that substance either by its senses or by its intellect. Now it is obvious that the soul does not apprehend a separate substance by its senses, because separate substances are not sensible things. Neither are separate substances apprehended by the soul’s intellect, because its intellect does not know singulars, and separate substances are singular substances. (Cf. Aristotle, On the Soul 2.5, 417b23; Averroes, Commentary on Aristotle’s On the Soul, bk. 2, comm. 60.) Therefore, the soul, existing apart from the body, can in no way understand separate substances. (Cf. Aquinas, On Truth, q. 8, a. 7, obj. 3.)

Obj. 6: Further, our potential intellect differs from an angel to a greater degree than our imagination does from our potential intellect, for our imagination and potential intellect are rooted in one and the same substance of the soul. Now our imagination can in no way understand our potential intellect. Consequently, our potential intellect can in no way apprehend a separate substance.

Obj. 7: Further, as our will is ordered to good, so is our intellect ordered to truth. But the will of some separated souls, namely, those of the damned, cannot be ordered to good. Therefore, neither can their intellect in any way be ordered to truth which the intellect itself pursues above all else in its knowledge of a separate substance. Therefore, not every separated soul can know a separate substance.

Obj. 8: Further, as we have pointed out already, (Above: q. 16; cf. ST I.89.2, obj. 3.) ultimate happiness, according to the philosophers, is thought to consist in the knowledge of separate substances. (Cf. Avicenna, De anima, part 5, ch. 6; Algazel, Metaphysics, bk. 2, tr. 5.) Now if the souls of the damned understand separate substances, which we here on earth cannot understand, it seems that the damned are nearer to happiness than we are. This is incongruous.

Obj. 9: Further, one intelligence knows another through knowing its own essence, as is pointed out in the work Book of Causes. (The Book of Causes, proposition 7 [8]; cf. Aquinas, On Truth, q. 8, a. 7, resp.; SCG II.98.) Now apparently the separated soul cannot know its own essence, because the potential intellect can know itself only through species abstracted from phantasms, as is stated in On the Soul 3. (Aristotle, On the Soul 3.8, 430a2–9; 432a6.) Consequently, the separated soul cannot know separate substances.

Obj. 10: Further, there are two ways of acquiring knowledge: (Cf. Aristotle, Prior Analytics 2.23, 68b13; Posterior Analytics 1.2, 71b30–72a5; 1.13, 78a22–b12; 1.18, 81a39; Physics 1.1, 184a16–21; Aquinas, Commentary on Aristotle’s Posterior Analytics, bk. 1, lect. 4, 8, 23; Commentary on Aristotle’s On the Soul, bk. 2, lect. 3; On Truth, q. 8, a. 15, s.c. 1.) first, by proceeding from what is subsequent to what is prior, and thus things which are better known absolutely are known by us through those things which are less known absolutely; second, by proceeding from what is prior to what is subsequent, and thus things which are better known absolutely are known first by us.

Now the first manner of knowing cannot be found in souls existing apart from bodies, for that manner of knowing is proper to us so far as we derive our knowledge from the senses. Consequently, the separated soul understands in the second manner, namely, by proceeding from what is prior to what is subsequent; and then those things which are better known absolutely are known first by the soul. But that which is best known is the divine essence. (Cf. Bonaventure, The Journey of the Mind to God, bk. 5, ch. 3.) Therefore, if the separated soul knows separate substances by its nature, it seems that it can grasp the divine essence, which is life eternal, through natural things alone. This is contrary to the Apostle, who says, the free gift of God is eternal life in Christ Jesus our Lord (Rom 4:23). (It is in fact Romans 6:23.)

Obj. 11: Further, a separate substance of an inferior order understands another separate substance of a higher order by reason of the fact that an impression of the superior substance is present in the inferior one. But the impression of a separate substance is present in the separated soul in a much more imperfect way than it is in the separate substance itself. Therefore, the separated soul cannot understand a separate substance.

On the contrary, like things are known by like. (Cf. Aristotle, On the Soul 1.2, 404b17–18.) Now the separated soul is a separate substance. Consequently, it can understand separate substances.

I answer that, in view of the things held by faith, it is seen that we must truly maintain that separated souls know separate substances. For the separate substances, to whose society the separated souls of men both good and bad are allotted, are called angels and demons. Now it does not seem credible that the souls of the damned do not know the demons whose society they share, and who are said to terrify the souls. Again, it seems even less likely that the souls of the good do not know the angels whose society they enjoy.

Moreover, the fact that souls existing apart from bodies know separate substances wherever they may be is in accord with reason. (Cf. SCG III.49.) For it is clear that the human soul, when joined to the body, has a direct knowledge of inferior things because of its union with the body. (Cf. Avicenna, De anima, part 5, ch. 3.) Wherefore, the soul is perfected only by what it receives from inferior things, namely, by species abstracted from phantasms. Consequently, the soul can acquire a knowledge of itself and of other things only inasmuch as it is led thereto through the aforementioned species, as was explained above. (Above: q. 16, resp., and ad 8.)

However, when the soul really will be separated from the body, its vision will not be directed toward inferior beings in order to receive species therefrom, rather will it be independent and capable of receiving infused species from superior substances without turning to phantasms which will then be wholly non-existent. The soul will be actuated by infused species of this kind and thus will know itself directly by understanding its own essence, and not in an a posteriori (Cf. SCG II.98.) fashion as it does in its present state. (Cf. ST I.89.2, resp.; SCG III.45.) Moreover, by its essence the soul belongs to the genus of separate intellectual substances, although it is the lowest in this genus, and possesses the same mode of subsisting; for every separate substance is a subsisting form. (Cf. ST I.88.2, ad 4; SCG III.46; above: q. 7, ad 17.)

Therefore, just as one separate substance knows another by immediately understanding its own essence, inasmuch as there is in its own essence some likeness of the other substance which it knows, either because it receives infused species from that substance, or from a superior one that is the common cause of both of them, so also does the separated soul, by immediately understanding its own essence, know separate substances by reason of the infused species received from them, or from the highest cause, namely, God. (Cf. SCG II.98; above: q. 7, ad 8.) However, the soul does not by its natural knowledge understand separate substances as perfectly as they understand themselves, because the soul is the most inferior of all intelligences and receives the emanation of intelligible light in the least degree. (Cf. ST I.89.2, resp.)

Reply Obj. 1: When the soul is united to the body, it is in a certain respect more perfect than when it is separated from the body. However, with respect to its act of understanding, the soul has a certain perfection, when separated from the body, which it cannot have while united to the body. (Cf. ST I.89.2, ad 1.) Nor is this incongruous, because intellectual operation is proper to the soul inasmuch as it surpasses the capacity of the body, for the intellect is not the act of any bodily organ. (Cf. Aristotle, On the Soul 3.2, 426a28; 3.4, 429a24–25; 429b5; Aquinas, Commentary on Aristotle’s On the Soul, bk. 2, lect. 26, n. 597; bk. 3, lect. 1, n. 687.)

Reply Obj. 2: We are speaking here of that knowledge of the separated souls which belongs to them by their nature; for when we speak of the knowledge which is given to them by grace, they are equal to the angels in knowing. (Cf. ST I.89.2, resp.) Moreover, this knowledge, whereby the soul knows separate substances in the aforesaid way, is not natural to the soul absolutely, but inasmuch as it is separated from the body. Therefore, the soul is not capable of this knowledge inasmuch as it is united to the body.

Reply Obj. 3: The highest perfection of the human soul’s knowledge consists in understanding separate substances. (Cf. Aquinas, Commentary on Boethius’s De Trinitate, q. 6, a. 4, ad 3; ST I.89.2, ad 3; above: q. 16, ad 1.) But it can obtain possession of this knowledge more perfectly by being united to the body, because it is disposed to this end by study and particularly by merit. (ST II-II.167.1, resp.; In IV Sent., d. 45, q. 3, a. 3, ad 4; cf. Augustine, On the Customs of the Church and the Manichees, bk. 1, cc. 21, 38 (CSEL 90:43; PL 32:1327).) Consequently, it is not united to the body unnecessarily.

Reply Obj. 4: When the soul is separated from the body, it does not know a separate substance through the essence of such a substance, but through a species and likeness of it. Moreover, it must be observed that a species through which something is known is not always abstracted from the thing that is known through that species, but only when the knower receives the species from the thing itself. When this is the case, the species is received in a simpler and more immaterial way in the knower than it is in the thing that is known through it. Indeed, if the opposite were true, namely, that the thing known is more immaterial and simpler than the knower, then the species of the thing known in the knower is not said to be abstracted, but to be impressed and infused. (Cf. Aquinas, Quodlibet III, q. 3, a. 2.) This is the way it is considered in this argument.

Reply Obj. 5: To know a singular is incompatible with our intellectual cognition only inasmuch as the singular is individuated by this matter; for our intelligible species must be abstracted from matter. Indeed, if any singulars exist in which the nature of the species is not individuated by matter, but each is a certain nature whose species subsists immaterially, each of them will be intelligible in virtue of its own nature. (Cf. Averroes, Commentary on Aristotle’s Metaphysics, bk. 12, comm. 51.) Separate substances are singulars of this specific type.

Reply Obj. 6: An imagination and a human potential intellect are more appropriate to the human subject than a human potential intellect and an angelic intellect. However, these are more in keeping with the species and nature because both of these belong to a thing having an intellective mode of existing. Moreover, an action is the natural effect of the form according to the nature of its species, and not of the subject itself. (Cf. Aquinas, Commentary on Aristotle’s On the Soul, bk. 3, lect. 1; Commentary on Aristotle’s On Sense and What Is Sensed, tract. 1, ch. 9.) Therefore, so far as conformity of action is concerned, more attention must be paid to the conformity of two forms that are of the same species existing in different substances than to the conformity of forms different in species existing in the same subject.

Reply Obj. 7: The damned are diverted from their ultimate end, and for this reason their wills do not tend to a good in keeping with this order. Moreover, their wills do tend toward some good because even the demons, as Dionysius says in chapter 4 of On the Divine Names, desire what is good and best, to live, to exist, and to understand; (Pseudo-Dionysius, On the Divine Names, ch. 4, para. 23 (PG 3:723–26); cf. Aquinas, On Evil, q. 16, a. 3, resp.) but this good is not ordered to the highest good, and, hence, their wills are perverse. Therefore, nothing prevents the souls of the damned from understanding many truths, but they do not understand the first truth, namely, God, the vision of whom causes happiness.

Reply Obj. 8: The ultimate happiness of man does not consist in knowing any created thing, but in knowing God alone; wherefore, Augustine says in his work Confessions, happy is he who knows you, though he does not know not these—namely, creatures; but unhappy is he who knows these and does not know you. And whoever knows both you and them, is not the happier for them but for you only. (Augustine, Confessions, bk. 5, ch. 4 (CSEL 33:93–94; PL 32:708–9; CCSL 27:60).) Therefore, although the damned know some of the things that we know, nevertheless they are much farther away from true happiness than we are, for we can attain it whereas they are unable to do so.

Reply Obj. 9: The human soul will know itself in one way when it will be separated from the body, and in another way when it is united to the body, as we have explained above. (Above: q. 15.)

Reply Obj. 10: Although that mode of knowing by which the soul knows better the things which are better known in themselves is proper to the separated soul, nevertheless it does not follow that the separated soul, or any other created separate substance, through its own nature and essence, can understand God. (Cf. SCG III.49.) For just as separate substances possess a more excellent mode of existing than material substances, so does God possess a more excellent mode of existing than all separate substances. For in material beings three things have to be taken into consideration, none of which is the same as the others, namely, the individual, the specific nature, and the act of existing. (Cf. Aquinas, On Being and Essence, ch. 5.) For we cannot say that this man is his humanity, because humanity is comprised only of the principles of the species; but this man adds individuating principles over and above the principles of the species inasmuch as the nature of the species is received and individuated in this matter. Likewise, humanity is not a man’s act of existing. However, in separate substances the nature of the species is not received in any individuating matter, because separate substances are immaterial, but the nature of the species is the nature itself subsisting in virtue of itself. (Cf. Aquinas, On Being and Essence, cc. 4–5; Commentary on Boethius’s Hebdomads, lect. 2; ST I.50.2, ad 3.) Consequently, in them the thing having a quiddity and the quiddity itself are one and the same, although their act of existing and quiddity differ from each other. (Cf. Aquinas, On Being and Essence, ch. 4; SCG II.53–54; ST I.75.5, ad 4; On Spiritual Creatures, a. 1, resp.) Only God is his own subsisting act of existing. (Cf. SCG I.22; II.16; ST I.3.4, resp.; I.44.1, resp.) Therefore, as we cannot know separate substances by knowing material quiddities, neither can separate substances know the divine essence by knowing their own substance. (Cf. Aquinas, On Truth, q. 8, a. 3, resp.)

Reply Obj. 11: It does not follow, because the impressions of separate substances are received in the separated soul in an imperfect way, that separated souls cannot know separate substances, but only that they know them imperfectly.