Chapter 55 — That intellectual substances are incorruptible

From the foregoing it is clearly shown that every intellectual substance is incorruptible.

For all corruption consists in separation of form from matter: simple corruption from separation of the substantial form, relative corruption from separation of an accidental form. For the thing must exist so long as the form remains, since by the form the substance is made the proper recipient of being. But where there is not composition of form and matter, there can be no separation of the same: therefore, neither can there be corruption. Now it has been proved (Ch. 50.) that no intellectual substance is composed of matter and form. Therefore, no intellectual substance is corruptible.

Moreover. That which belongs to a thing essentially is necessarily in it always and inseparably: thus roundness is essentially in a circle and accidentally in a coin; therefore, it is possible for a coin to be made not round, whereas it is impossible for a circle not to be round. Now, being is an essential consequence of form, for “essential” means according as it is such, (Aristotle, Posterior Analytics 1.4, 73b26–31.) and a thing has being according as it has a form. Hence substances that are not themselves forms can be deprived of being insofar as they lose a form, just as a coin is deprived of roundness according as it ceases to be round. However, substances that are themselves forms can never be deprived of being: thus if a circle were a substance, it could never be made not round. Now, it was shown above (Ch. 51.) that intellectual substances are themselves subsistent forms; therefore, they cannot possibly cease to exist, and consequently they are incorruptible.

Further. In every corruption potency remains after the removal of act: for a thing is not corrupted into nonbeing, just as neither is a thing generated from absolute non-being. But in intellectual substances, as we have proved, (Ch. 53.) the act is being itself, while the substance is by way of potency. Consequently if an intellectual substance were corrupted, it will remain after its corruption: which is utterly impossible. Therefore, every intellectual substance is incorruptible.

Again. In every thing that is corrupted there must be potency to non-being. Therefore, if there be a thing in which there is not potency to non-being, such a thing is not corruptible. Now there is no potency to non-being in an intellectual substance. For it is clear from what we have said (Ch. 54.) that a complete substance is the proper recipient of being. But the proper recipient of an act is compared as potency to that act in such a way that it is in no way in potency to the opposite: thus fire is compared to heat in such a way that it is in no way in potency to cold. Consequently, neither in corruptible substances is there potency to non-being in the complete substance except by reason of the matter. But there is no matter in intellectual substances, for they are complete simple substances. (Ch. 51.) Hence there is no potency to non-being in them. Therefore, they are incorruptible.

Further. In whatever things are composed of potency and act, that which holds the place of first potency, or of first subject, is incorruptible: therefore, even in corruptible substances prime matter is incorruptible. Now in intellectual substances that which holds the place of first potency and subject is their complete substance. Therefore, their substance is itself incorruptible. But things are only corruptible if their substances are corruptible: therefore, all intellectual natures are incorruptible.

Moreover. Whatsoever is corrupted, is corrupted either essentially or accidentally. But intellectual substances cannot be corrupted essentially. For all corruption is by a contrary. For an agent, since it acts according as it is an actual being, always brings something into actual being by its action. Consequently, if by this same actual being, something is corrupted through ceasing from actual being, this must result from their mutual contrariety, since contraries are things which exclude one another. (Aristotle, Categories, ch. 8, 10b12–11a4; ch. 10, 11b33–12a4.) Hence whatsoever is corrupted essentially must either have a contrary, or be composed of contraries. But neither of these can be said of intellectual substances. A sign of this is that in the intellect things even of contrary nature cease to be contraries: for white and black are not contraries in the intellect, since they do not exclude one another (in fact, rather do they follow from one another, seeing that by understanding the one we understand the other). Therefore, intellectual substances are not corruptible essentially. Moreover, neither are they corrupted accidentally. For thus accidents and non-subsistent forms are corrupted. Now it was shown above (Ch. 51.) that intellectual substances are subsistent. Therefore, they are altogether incorruptible.

Further. Corruption is a kind of change: and change must be the term of a movement, as is proved in the Physics. (Aristotle, Physics 5.1, 224a30–b12.) Consequently, whatsoever is corrupted must be moved. Now it was proved in the Physics (Aristotle, Physics 6.4, 234b10–20.) that whatsoever is moved is a body. Hence it follows that whatsoever is corrupted is moved—if it be corrupted per se—or else that it is a form or a bodily force dependent on a body, if it be corrupted accidentally. But intellectual substances are neither bodies, nor forces or forms dependent on a body. (Ch. 49.) Therefore, they are not corrupted either essentially or accidentally: and consequently they are altogether incorruptible.

Again. Whatsoever is corrupted, is corrupted through being passive to something, since to be corrupted is itself to be passive. Now no intellectual substance can be passive with such a passion as leads to corruption, because to be passive is to be receptive, and that which is received into an intellectual substance must be received according to its mode, namely, intelligibly. Now that which is thus received into an intellectual substance perfects the intellectual substance and does not corrupt it, since the intelligible is the perfection of the intelligent. Therefore, an intelligent substance is incorruptible.

Further. Just as the sensible is the object of sense, so the intelligible is the object of the intellect. But the sense is not corrupted by a proper corruption except through being excelled by its object: for instance, the sight by very brilliant objects, and the hearing by very loud sounds, and so on. And I say “by proper corruption,” because the sense is also corrupted accidentally on account of its subject being corrupted. This kind of corruption, however, cannot happen to the intellect, since it is not the act of any body, as depending on the body, as we have proved above. (Ch. 51.) And it is clear that it is not corrupted through being excelled by its object, because he who understands very intelligible things understands things less intelligible not less but more. (Aristotle, On the Soul 3.4, 429b1–4.) Therefore, the intellect is in no way corruptible.

Moreover. The intelligible is the proper perfection of the intellect: hence the intellect in act and the intelligible in act are one. (Aristotle, On the Soul 3.4, 429b26–430a3.) Accordingly, whatever is applicable to the intelligible as such must be applicable to the intellect as such, since perfection and perfectible belong to the one genus. Now the intelligible, as such, is necessary and incorruptible, for necessary things are perfectly knowable by the intellect: whereas contingent things, as such, are only deficiently knowable, because about them we have not science but opinion, so that the intellect has science about corruptibles insofar as they are incorruptible (that is, according as they are universal). Therefore, it follows that the intellect is incorruptible.

Again. A thing is perfected according to the mode of its substance. Consequently, we can gather the mode of a thing’s substance from the mode of its perfection. Now the intellect is not perfected by movement, but by the fact of its being outside movement: for we are perfected by science and prudence as regards the intellective soul, when the movement both of the body and of the soul’s passions are subdued, as the Philosopher states in Physics 7. (Aristotle, Physics 7.3, 247b22–248a28.) Hence the mode of an intelligent substance is that its being is superior to movement, and consequently superior to time—whereas the being of every corruptible thing is subject to movement and time. Therefore, it is impossible that an intelligent substance be corruptible.

Further. It is impossible for a natural desire to be vain, since nature does nothing in vain. (Aristotle, On the Heavens 2.11.) Now every intelligent being naturally desires everlasting being, and to be everlastingly not merely in its species, but also in the individual. This is proved as follows. The natural appetite, in some, results from apprehension: thus the wolf naturally desires the slaying of the animals on which it feeds, and man naturally desires happiness. In some it results without apprehension from the sole inclination of their natural principles, which inclination is, in some, called the natural appetite; thus a heavy body desires to be below.

In both ways, things have a natural desire for being, a sign of which is that not only things devoid of knowledge resist corruptives according to the power of their natural principles, but also those which have knowledge resist the same according to the mode of their knowledge. Consequently, those things lacking knowledge in whose principles there is a power of perpetuating their being (so that they remain ever the same as to individual identity) naturally desire to be perpetuated even in their individual identity: whereas those whose principles contain no such power, but only the power of perpetuating their being in the same species, desire also to be perpetuated in this way.

Hence we must observe this same difference in those things which have a desire of being together with knowledge; namely, so that those who have no knowledge of being except as “now” desire to be as now, but not to be always, because they do not apprehend perpetual being. Yet they desire perpetuity of the species: although without knowledge, because the generative power, which conduces to this effect, is a preamble, and not a subject of knowledge. Therefore, those things which know and apprehend perpetual being desire it with the natural desire. Now this applies to all intelligent substances. Therefore, all intelligent substances, by their natural appetite, desire to be always: consequently, it is impossible that they cease to be.

Further. Whatever things begin to be and cease have both through the same potency, because the same potency regards being and not being. Now intelligent substances could not begin to be except through the potency of the first agent, since they are not made out of matter that could exist before them, as we have proved. (Ch. 49.) Consequently, there is no potency in respect of their not being, except in the first agent insofar as he is able not to pour being into them. But nothing can be said to be corruptible by reason of this potency alone: both because things are said to be necessary and contingent according to a potency that is in them, and not according to God’s potency, as we proved above, (Ch. 30.) and because God, the author of nature, does not take from things that which is proper to their respective natures. It was shown above that perpetual being is a property of intellectual natures; hence God will not take this from them. Therefore, intellectual substances are in every way incorruptible.

Hence in the Psalm, praise the Lord from the heavens, after mentioning together the angels and heavenly bodies, the text continues: he established them forever and ever (Ps 148:1, 6), thus designating the perpetuity of the aforesaid.

Dionysius also says, in On the Divine Names 4, that on account of the rays of the divine goodness, the intelligible and intellectual substances subsist, are, and live: and their life never fails nor diminishes, for they are free from the universal corruption, knowing neither generation nor death, and they are raised above restless and ever-flowing change.