In De ente et essentia D. Thomae Aquinatis commentaria

It is explained how accidents have an essence, how they are distinguished from substance and from one another, and how they are related to logical intentions.

It remains now to see how essence is in accidents; how it is in all substances has been said. Since, as was said, essence is signified by definition, they must have essence in the same way in which they have definition. They have an incomplete definition, because they cannot be defined unless a subject is placed in their definition. This is because they do not have absolute existence in themselves apart from a subject; but just as substantial existence remains from form and matter when they are composed, so accidental existence remains from accident and subject when the accident comes to the subject. Hence neither substantial form nor matter has a complete essence: in the definition of substantial form that of which it is the form must be posited, and in the definition of matter its form must be posited. This is because neither is a complete species in the genus of being, but each is part of a species. Thus neither can be defined without adding the other, as is said in Metaphysics VII, text 45. Accidents, however, do not have a complete essence, nor are they part of a complete essence, because they do not constitute a species in the genus of substance. Hence, just as they are beings according to a qualification, so they have an essence according to a qualification.

Nevertheless, there is this difference between substantial and accidental forms: just as substantial form, joined to matter, causes the substantial existence of the composite, so accidental form causes a certain second existence, without which the subsisting thing can still be understood to exist, just as the first can be understood without the second, or a predicate without a subject. Hence accident and subject do not make one per se, but one per accidens. Their conjunction therefore does not produce a certain essence, as the conjunction of form with matter does; for this reason an accident has neither the character of a complete essence nor of a part of a complete essence, but, just as it is a being according to a qualification, so it has an essence according to a qualification.

In this third treatise, contained in one chapter, accidents are determined so that nothing within the breadth of being remains untouched. It is divided into three parts: in the first, what essence signifies in accidents is explained; in the second, the diversity of accidents from substance and from one another; in the third, how they stand in relation to logical intentions. He therefore explains the first with this conclusion. Accidents have an incomplete essence. It is proved thus: whatever have an incomplete definition have an incomplete essence; accidents have an incomplete definition; therefore they have an incomplete essence. The major is clear from the fact that essence is what is signified by definition, as was said at the beginning of the book.

The proof of the minor is this: whatever are necessarily defined through something outside their essence have an incomplete definition; for the definition of such things is not completed through intrinsic principles but needs an extrinsic addition. But accidents are necessarily defined through something outside their essence; their subject must be placed in their definition, as is said in Metaphysics VII, text 15; therefore accidents have an incomplete definition.

To manifest the minor more clearly, St. Thomas in the text compares accidents with substantial forms according to their agreement and difference. It will thereby be clear how accidents have an incomplete essence.

He says that accidents agree with substantial forms in three respects. First, neither has absolute existence independent of a subject or receptive principle. Just as existence common to both flows from substantial form joined to matter, so existence common to both remains from the conjunction of accident with subject: from the conjunction of whiteness with snow there arises the existence by which whiteness exists and snow is white.

Second, they agree in that neither has a complete essence, because the essence of each is essentially referred to another as receptive. Substantial form is essentially an entity perfecting matter, while an accident is essentially an entity qualifying a subject.

Third, they agree in that neither has a complete definition in its own terms, but only through an addition. Just as the subject of an accident, which lies outside its genus, must be placed in its definition, so the receptive principle of substantial form—matter, which lies outside its proper genus—must be placed in the definition of substantial form. For the genus of form is act, as is clear in On the Soul II; while matter, since being is divided into act and potency, is clearly contained under potency and consequently lies outside act, which is the genus of form. Aristotle showed this when defining soul, placing in its definition an organic physical body, which is the proper matter of soul insofar as soul is the perfection of a physical body. He added this so that you would not wonder why matter is not placed in the definition of soul, although soul is a substantial form, but a physical body is. The reason is that the physicist does not consider soul as substantial form, but as soul, which as such presupposes a physical body as its proper matter. Hence it follows that to consider the intellectual soul as such according to its complete quiddity is not the work of the physicist, as Aristotle also teaches in Book I of On the Parts of Animals, chapter I.

They differ in five respects. First, the receptive principle of substantial form does not have existence in itself without the existence of the form, and in this it conforms to its form. Just as substantial form has no existence apart from its receptive principle, so neither does its receptive principle have existence apart from its form. But the receptive principle of an accident has existence in itself apart from the existence of its accident. The reason is that the receptive principle of substantial form is a being in pure potency, whereas the receptive principle of an accidental form has existence in act.

Second, they differ because from the conjunction of substantial form with its receptive principle there emanates the existence by which the thing itself subsists, or simply is. From the conjunction of accidental form with its subject flows the existence by which the thing is according to a qualification. This difference arises from the first: since the receptive principle of substantial form lacks existence in itself, the existence flowing from the form is primary; conversely, since the subject of an accident enjoys its own existence, by acquiring the accident it acquires such existence, not existence simply, which it already possesses. Thus the first existence can be understood without the second: substance can be separated from an accident, as is said in Metaphysics VII, text 4.

Third, they differ because from the composition of substantial form with its subject there results one per se. From the composition of accident with subject there results one only per accidens. This difference arises from the second: since from substantial form there results existence simply, by which the thing is per se, one simply must result, by which the thing is one per se, for being follows unity. But since subject and accident have two existences, they cannot make one per se for the same reason: unity follows being, and unity per se cannot follow being per accidens.

Fourth, they differ because from the conjunction of substantial form with matter there results a certain third essence, namely entity. From the conjunction of accident with subject no third essence results. This difference arises from the third: since essence is what is signified by definition, as the defined thing, and the defined thing must be one per se according to Aristotle in Metaphysics VII, text 16, it follows that, since accident and subject do not make one per se, no essence results; conversely, since substantial form and matter make one per se, a third essence results.

Fifth, they differ because, although substantial form is not a complete essence, it is nevertheless a part of a complete essence. An accident, however, is neither a complete essence nor a part of a complete essence. This fifth difference follows from the fourth. If form and matter make a certain third essence, substantial form will be a part of it. But if no essence results from accident and subject, the accident can be posited as a part of no complete essence. Thus an accident is an incomplete and qualified being and consequently has an incomplete essence and definition. Nor should it disturb you that substantial form has just been said not to be absolute from its receptive principle and not to have existence without matter, while above it was said that the intellectual soul remains independent of and really separated from matter. The latter is simply true. To verify what we have just said, it is enough that the intellectual soul essentially informs matter and is, in this respect, inseparable from it according to quidditative existence, as its definition shows; and that substantial form as such has no basis for being absolute from matter and independent of it according to actual existence, although this may belong to some substantial form for another reason, for example because it is intellectual. We are speaking of substantial form as the form of a part, as such.

Many doubts arise concerning these statements. Regarding the second agreement, it is doubted whether what is said there is true, namely, that accidental essences are essentially not absolute from a receptive principle. This doubt is accompanied by another concerning the third agreement: whether accidents are necessarily defined through a subject.

Questions also arise concerning the differences assigned. The first has a doubt concerning both members together with their root: whether substantial form is only the act of pure potency.

And whether accidental form is received only in a being in act.

Regarding the second difference, there is a doubt whether accidents have their own existence, really distinct from substantial existence.

There is again a doubt there: whether a substance subjected to an accident can be understood to exist without any accident at all.

If we wished to treat these six doubts at length, we would go beyond the limits of our purpose, since that belongs to another undertaking. But, so that we do not pass over them wholly without nourishment, something will be said about several of them in the order stated above, bringing forward both our foundations and those of our adversaries.

Whether aptitudinal inherence belongs to the essence of an accident.

Regarding the first doubt, after the title has first been clarified, Scotus’s opinion will be brought forward; second, that of St. Thomas; third, the arguments on the contrary will be answered. The sense of the first doubt, then, is whether dependence upon a subject belongs to the essence of an accident: this is what others question under more specialized terms when they ask whether aptitudinal inherence belongs to the essence of an accident. Scotus, in IV Sent., dist. XII, q. I, decides this question with respect to absolute accidents, namely quantity and quality; and he says that those who turn this into a doubt are ignorant of the meaning of inherence itself. He is content with a single argument to prove that it is impossible for any inherence to belong to the essence of an absolute accident, as follows. No relation belongs to the formal concept of an absolute thing; every inherence is a relation; therefore no inherence belongs to the formal concept of an absolute thing.

The same argument is formulated differently by him, as follows: That which is essentially toward itself does not essentially include a relation, according to Augustine, On the Trinity VII, chapter II; but an absolute accident is toward itself; therefore an absolute accident does not essentially include a relation, whereas inherence is a relation; therefore.

Others confirm the same argument as follows: Everything that is said relatively is something beyond the relation; for the foundation of a relation is formally other than the relation; but an absolute accident, for example quality, is said relatively to be inherent; therefore it is something absolute beyond inherence. Moreover. Aptitudinal inherence belongs to the essence of an accident; therefore quantity and quality are not the most general genera. The consequence holds because then a common quidditative concept of the same account in all of them could be abstracted from quantity, quality, and the remaining accidents, inferior to the concept of being and superior to those nine genera, namely being in; and thus, since every such concept is a genus, the nine most general genera of accidents would not be most general, for they would have a genus supervening upon them.

The opinion of the Thomists, however, is that aptitudinal inherence belongs to the essence of an accident, and that it is not a relation.

For it must be known that something is absolute or relative in two ways, namely from a subject and from a term. An entity absolute from a subject is that which is not naturally received in another, such as substance. Something relative to another as a subject is that which is essentially naturally received in another, such as every accident. That which is absolute from a term is that which formally does not regard another precisely as a term toward which it is directed, such as substance, quantity, and quality. That which is relative to another as a term is that which formally regards another precisely as the term toward which it is directed, as does the category of relation. For in this the relation belonging to the category of relation differs from the other respects of the remaining genera, which some call transcendental: the respect belonging to the genus toward something is essentially toward another, not as a recipient or an efficient, final, or formal cause, but precisely toward another as a term; for one of the relatives is neither the form nor the end nor the efficient cause of the other, but a term. For this reason Albert the Great says that one of the relatives is not to be defined through the other, because the word through denotes causality.

The respect of the other genera, which for lack of vocabulary is called a respect, essentially regards another; but as a subject, matter, form, and things of this kind. Thus matter essentially regards form, and conversely, as was said above concerning the commensuration of the intellectual soul. Since, then, aptitudinal inherence imports a respect toward another as recipient, we say that it is not of the genus of relation, but identified with each genus, signifying now an absolute entity and now a relative one. Hence aptitudinal inherence is not prevented from belonging to the essence of an absolute accident by the fact that it is a respect; indeed, from the fact that an absolute accident is not absolute from a subject, though it is absolute from a term, it follows that an essential dependence upon a subject belongs to its essence, which aptitudinal inherence explains.

Our position is shown to be consonant with reason by the fact that just as being toward constitutes the accident of relation, so being in constitutes the universal accident. For being is contracted through being in into the nine genera of accidents; and therefore, just as toward belongs to the essence of relation, so in belongs to the essence of an accident. Hence Simplicius, in his commentary on the Categories, says that being in constitutes no genus, but encompasses every accident.

This is confirmed by the fact that unless aptitudinal inherence belonged to the essence of an accident, the accident itself could be conceived, once its definition were complete, without aptitudinal inherence being posited in its definition; which is impossible. For it must have in its definition an essential dependence upon a subject, which aptitudinal inherence explains; otherwise there would be no need of a subject for defining it. Therefore St. Thomas says in many places that the definition of an accident is this or something of the same kind: A thing to which being in another is due. So much for the second point.

To the first argument on the contrary it is said that the minor premise of the first argument is false, and Scotus appears to have been deceived because he did not see the difference between the respect In and Toward. For the respect In is not a relation. Although such a respect terminates at a subject, and consequently the subject is a term, nevertheless it does not terminate as a term, but as the recipient of that respect; and this must be carefully attended to here. For it is one thing to say, “A is the term of such a respect,” and another to say, “A terminates such a respect as a term,” as is clear from what has been said.

And through this the response is clear both to the second and to the third form of the same argument; for it always supposes that aptitudinal inherence is a relation.

To the last argument the consequence is denied: for it is said that being in has different accounts in the categories, just as being does. For in is analogical with respect to the nine genera of accidents, just as being is with respect to all genera.

From these things the solution of the second doubt is clear, in which Scotus agrees with us in IV, dist. XII, so that we unanimously confess that an accident cannot be completely defined without the addition of a subject, as has now been proved: this will become clearer below, when it has been explained from where genus and difference are taken in these things. Aristotle also testifies to this in Metaphysics VII, texts XV and XVII.

Let the third doubt, since it is too extensive, be left to be discussed elsewhere; for its full resolution would have to fill many quires.

Whether undetermined dimensions precede substantial form in matter. Averroes’s opinion on the Substance of the Orb, chapter I, column 2; Physics I, chapter LXIII; and Physics IV, chapter XXV.

The fourth [doubt], since it concerns the nature of accidents, whose treatment we are undertaking, I do not think should be entirely passed over. Three things must be done concerning it: first, Averroes’s opinion will be recounted; second, the opinion of St. Thomas will be set forth; third, the arguments on the contrary will be answered.

Regarding the first, it must be known that Averroes founded the opinion contrary to ours in his book On the Substance of the Orb, positing undetermined dimensions in prime matter, which is pure potency. From this it follows that not every accident is subjectively in a being in act.

He is moved to hold this by several arguments leading to an impossibility. The first is: An undetermined dimension is not coeternal with matter; therefore a body comes to be from what is not a body, and a dimension from what is not a dimension; and finally it follows that bodily forms, that is, dimensions, are contrary to one another and succeed one another in a subject, just as substantial forms succeed one another in the same matter. The consequence is impossible; therefore, by destruction of the consequent, and so on. The impossibility of the consequent is clear from the fact that neither motion nor any change is toward an undetermined quantity. For increase is toward a determinate quantity. It is also clear from the fact that nothing is contrary to quantity, as is said in the Categories. The consequence is proved from the fact that everything which comes to be comes to be from its contrary or privation, as is said in Physics I, text LXIV, and V of the same work, text VII.

The second argument is this: Undetermined quantity is not in matter; therefore matter cannot receive forms distinct in species or number at the same time. The consequent is false to the senses; therefore. The consequence is proved from the fact that diverse forms cannot be received at the same time except in diverse parts of matter; but matter lacks diverse parts before receiving quantity. For substance, with quantity excluded, is indivisible, as is said in Physics I, text XV.

The third argument is this: Quantity is not subjectively in matter; therefore form is not divided by the division of matter. The consequence holds because form is received in indivisible matter, since matter is posited as lacking quantity. Further: therefore a form received in matter has no division. The consequence holds because every division of a material form presupposes diversity of parts in matter. Further: therefore a form received in matter is eternal and lacks a contrary. The consequence holds because the temporality of a form follows its corruptibility; but no form is corruptible unless its receptacle has diverse parts, one of which is informed by that form and the other by another form. For things that mutually corrupt one another must be communicated in matter, as is said in On Generation I, text LIII. Finally it follows that matter receives no form except the first; for the corruption of one must be the generation of another, as is said in On Generation I, text XVII, and consequently it lacks a contrary. So much for the first point.

Although St. Thomas follows this opinion in some of his books, he ultimately determined the opposite as his own opinion in the First Part, question LXXVI, article 6, where he uses this argument against Averroes’s position: Whenever something is in potency to every act, it first receives, in a certain order, the first act absolutely and then the subsequent acts; but prime matter in itself is in potency to all substantial and accidental acts in a certain order; therefore it first receives the act that is prior absolutely, and then the later one. But the first act absolutely, also in the order of generation, is being; therefore the first thing understood to be received in matter is substantial being, and this is received only from substantial form; therefore substantial form is received in matter before any accident, and thus every accident that follows comes to a being in act.

That being is the first act absolutely is clear both from the authority of the Book of Causes at its beginning and because being as to quantity presupposes being, and likewise being as to quality presupposes being; and so with the others. Moreover, many inconveniences follow from this position: namely, that being in a certain respect precedes being absolutely; that being per accidens is prior to being per se; that matter has a greater connection with a form of another genus than with a form of its own genus, since it can be stripped of any substantial form but not of every accidental form; and that generable substances have not only three but four principles, namely matter, form, privation, and undetermined quantity. For it cannot be imagined that quantity is not a principle at least per accidens, since it is joined to a per se principle, just as privation is said to be; and thus Aristotle ought to have counted it among the principles. Therefore St. Thomas’s opinion must be held: every accident is subjectively in a being in act, and by this differs from substantial form, which is subjectively in a being in pure potency. And so much for the second point.

To Averroes’s first argument it is said that the first consequent of those arguments has several senses and is sometimes true and sometimes false; therefore it must be distinguished. If the word “from” signifies the relation of material cause, it is true: a body comes to be from matter which is not a body and is indivisible in act, although it is a body and divisible in potency. But if “from” signifies the relation of the terminus from which, it is false: the matter from which a body comes to be must, immediately before that instant, have had corporeity. And universally, at every instant of time, it must itself be under dimensions. In this sense Aristotle in On the Heavens III, texts XXIX and LXIV, says that it is impossible for a body to come to be from what is not a body, that is, after what is not a body. Further, the phrase “comes to be” must be distinguished: it can be understood in two ways of a body or dimension. In one way terminatively, that is, as coming to be as the terminus of some motion or change; and in this way it is impossible for a dimension to come to be. In another way concomitatively, as being a consequence accompanying the terminus itself of motion or change; and in this way it is true that a body comes to be. For neither generation, alteration, nor local motion terminates at quantity as such, although increase terminates at perfect quantity. But when generation terminates per se and primarily at a substantial composite, its inseparable accidents are generated consecutively; quantity is among these, and it follows substantial corporeity.

The error, then, occurs in Averroes’s first argument: once the first consequence is granted, insofar as it infers the consequent in one sense, the second consequence does not hold, since it presupposes that dimensions come to be not concomitatively and per accidens but terminatively. For what comes to be as the terminus of changes is said to be corrupted by its contrary and to succeed one another by mutually expelling one another; this is not said of what comes to be consecutively, among which is undetermined quantity.

To the second argument the consequence is denied. In reply to its proof, it is said that diverse forms requiring diverse parts in matter can be understood in two ways. In one way, so that “before” signifies an order of time: in this sense it is true that any two forms to be received simultaneously in matter presuppose that it was divided into several parts immediately before the instant at which those forms are introduced. For the same part of matter cannot at once be suitably disposed for two forms by alteration. But this previously required distinction of the parts of matter need not be made through undetermined dimensions inhering in matter itself; it is made through the dimensions of preceding composites. In another way, “before” can signify an order of nature, so that at the instant when the forms are introduced it is necessary that matter have, by nature, a diversity of parts prior to the distinct forms. This is false: matter must by nature be prior to being distinct. Therefore, at and for that instant, two forms require distinct parts of matter, but they do not presuppose them.

To the third it is said that form’s being divided through the division of its subject can be understood in two ways. In one way, form has division from the subject because it is received in matter already divided; in this way, how it is true and how it is false has just been explained. In another way, form is divided upon the division of its subject because it has such division by reason of its subject; in this way it is true, since quantitative division belongs to substantial form from the fact that it is in matter, by reason of which the composite is quantified.

For just as quality follows the composite by reason of form, though not in such a way that the quality itself is subjectively present in the form, so quantity is in the composite by reason of matter, though not in such a way that it is present in matter. Therefore, since quantitative division belongs to form only by reason of matter, in which it is received, as forms separated from matter show, we concede that forms are divided upon the division of the subject, but not that this division precedes form; rather, it accompanies it. Hence the answer to the entire course of the argument is clear, since it collapses by resting on a false foundation. For it is founded on the claim that, according to our exposition, forms are not divided upon the division of the subject; and it is clear that this does not follow.

The fifth doubt, with the arguments omitted, has a true affirmative part according to St. Thomas’s teaching. Since some being flows from every form, because form is that which gives being to a thing, accidental being must flow from an accidental form, as being-white flows from whiteness and being-sweet from sweetness.

That the being which flows from an accidental form is not the same as substantial being is most evident from the proper accounts of substance and accident. For substantial being is being absolutely, according to itself, independent, and first; accidental being is being in a certain respect, dependent upon a subject in another, and posterior. Not only is the accident’s being of actual existence really distinct from the subject’s actual being, but it is also distinct from the very essence of the accidental form from which it comes. For it was proved above that no created quiddity is its own existence. Hence the existence of whiteness is neither whiteness itself, nor the existence of the subject, nor the reception of whiteness in the subject. Likewise the existence of substantial form is neither the form itself, nor matter, nor the reception of form in matter. Rather, just as substantial form, received in matter, perfects it so that both receive existence, so whiteness, received in a subject, perfects it so that it receives being-white. Thus, just as form is the reason why matter and the substantial composite have being, so whiteness is the reason why the subject, the composite of whiteness and subject, has such being, namely being-white. And just as there must be as many substantial beings in a thing as there are substantial forms, so accidental being is multiplied according to the number of accidental forms. Being-white is one thing, and being-sweet another. Therefore those who attributed to St. Thomas the opinion recounted by Scotus in IV Sentences, distinction XXII, are mistaken.

Concerning the sixth doubt, namely whether a substance subject to an accident can be understood to exist without any accident, the position of the holy Doctor must first be explained. Then a certain error must be eliminated.

To grasp the first point, it must be distinguished that we can speak of substance and accident in two ways. First, simply as such: of substance under the account of substance and of accident insofar as it is accident. In another way, we can speak of substance and accident under the account of this substance and this accident. In the first way substance is separable from every accident, because substantial being as such has no necessary connection with accidental being; otherwise every substance would be subject to an accident. In the second way substance cannot be separated from every accident: it cannot be separated from its proper property, because of the necessary connection between a subject and its proper property—not because the subject depends upon the property. Therefore St. Thomas says in the Disputed Questions on Spiritual Creatures, article last, reply to 7, and in the Questions on the Soul, article 12, reply to 7, that it is neither possible nor intelligible for a subject to exist without its proper property. In the text, however, speaking of substantial and accidental being as such, he says that a subject can exist without an accidental form arriving in it. He shows, by the nature of demonstration, that a subject cannot exist without a property: the conclusion which proves the inherence of a property in a subject must be necessary and impossible to be otherwise.

Here an intolerable error must be avoided, proposed by Antonio Trombetta in his Quodlibet, where he says that according to St. Thomas and his followers a subject is nothing but a material cause with respect to a property, and a property is an accident; from this it necessarily follows that a subject can exist without its proper property. The basis of this consequence is that every passive potency is a potency of contradiction; but a subject is only in passive potency with respect to a property; therefore it is in a potency of contradiction, and therefore can have the property and not have it. The major premise is found in Metaphysics IX, text XVII, and is also proved by reason as follows: The properties of being are distinct in such a way that one includes the negation of another; therefore potency includes the negation of act; consequently, insofar as it is potency, potency is not incompatible with existing without act; therefore every potency is a potency of contradiction.

Moreover, toward the same conclusion: The possible is intermediate between the necessary and the impossible; therefore, since the necessary regards being alone and the impossible non-being alone, the possible regards both being and non-being; and thus every potency, since the possible is spoken of through it, is a potency of contradiction.

Moreover, toward the same conclusion: Passive potency is toward being because it can receive being from another, namely an agent; but if it receives being from another, with that other excluded, insofar as it is in itself it is under non-being. If, therefore, passive potency in itself is under non-being and can have being from an agent, it necessarily follows that it is a potency of contradiction, namely a potency toward being and non-being.

The error occurs both in the principles and in the conclusion. In the principles: St. Thomas in the First Part, question LXXVII, article 7, expressly holds and proves that the subject is the cause of its proper property in three genera of cause, namely material, efficient, and final; hence the error of the minor premise is clear. Although the major premise is Aristotle’s, it is nevertheless badly understood and proved. For material potency is twofold: one is merely receptive, while the other is not only receptive but also passive, with the name “passion” extended to every kind of change. Merely receptive potency is necessarily coeval with its act, since if it existed before its act it would have to receive that act through some change, and thus would not be merely receptive with respect to it. Passive potency, however, is necessarily coeval with no act with respect to which it is passive, since it acquires every such act through change and consequently loses it through change; for everything generable is corruptible, as is said in On the Heavens I. Therefore the proposition “Every potency is a potency of contradiction” must be understood of passive potency, not of merely receptive potency. Both the sense itself and Aristotle’s text establish this gloss. To the senses it is clear that there is in the heavens a receptive potency for their shape, and yet such potency in them is not a potency of contradiction: the heavens are not in potency to another shape. Aristotle in the cited text of Metaphysics IX says that the heavens are not in potency to motion but only to its termini; yet it is evident that the heavens have a receptive potency for their motion. Thus he indicated that he was speaking of passive potency, since the heavens are in potency to the termini of motion. Therefore, since a subject has not passive but merely receptive potency with respect to its proper property—for no change intervenes between a subject and its property—the subject is not in a potency of contradiction with respect to the property; and so the conclusion drawn was false.

To the arguments by which the objector attempts to prove that proposition of every receptive potency, the response is as follows. To the first it is said that it is true that the properties of being are distinct in such a way that one includes the negation of another, because one is not formally the other: potency is not formally act. But it does not follow: therefore either can exist without the other. For this inference is invalid: “This is not that; therefore this can exist without that.”

To the second it is said that the possible, as distinguished against the necessary and the impossible, is taken from passive potency, not from merely receptive potency. Therefore it does not follow from this except that passive potency is a potency of contradiction, whereas the objector must prove that every receptive potency is a potency of contradiction.

To the third it is said that the first proposition brought forward there—namely, that potency is toward being because it can receive being from another, namely an agent—is true in one sense and false in another. If “can” signifies possibility as distinguished against impossibility, Aristotle says that it is false: its sense is that potency is toward being because it is not impossible for it to receive being from an agent. In this way the heavens would be in potency to motion, since they receive it from another. But if “can” signifies potency as distinguished against being in act, then the proposition is true. Something is in potency toward being because it can receive being which it does not yet have, just as something is in potency toward non-being because it can have the non-being which it lacks. But since every possible act that can be had is acquired by some potency only through change, we return to our position: only passive potency is toward being.

The other arguments by which the Scotists prove the separability of substance from every accident can easily be solved from what was said above. For they assume propositions whose falsity was explained earlier.

But since that which is called most and most truly such in each genus is the cause of those which come later in that genus, as fire, which is at the limit of heat, is the cause of heat in hot things, as is said in Metaphysics II, substance, which is the principle in the genus of being and has essence most and most truly, must be the cause of accidents, which participate in the account of being secondarily and, as it were, in a certain respect.

In this second part of the chapter, intending to explain the diversity of accidents among themselves, he first sets down the cause of accidents, so as to indicate their cause of diversity, with this conclusion: Substance is the cause of accidents. He proves it thus: What is most and most truly a being is the cause of the remaining beings; substance is most and most truly a being; therefore substance is the cause of the other beings. But such beings are accidents. The minor premise is clear from Metaphysics VII at the beginning. The major is taken from Metaphysics II, text IV, where it is said that universally whatever is most such in some order is the cause of all the others in that order, so that they may be: just as fire, which in the order of hot things is hottest, is the cause of all hot things being hot. In the text he uses the name of genus, just as Aristotle there uses univocation, because the truth of this proposition requires the cause to communicate with the effect in name and account, although the same thing may be so analogically. For it does not follow, “The heavens are the cause of all hot things; therefore the heavens are hottest,” though it would follow if the name “hot” belonged univocally to the heavens and hot things. Since, therefore, substance and accident agree analogically in the name and account of being, and substance is being most of all, it is the cause of all the others being beings.

This nevertheless occurs in different ways: because the parts of substance are matter and form, some accidents principally follow form and some matter. Since accidents are caused by the substance in which they are, and the diversity of effects comes from causes, he assigns the diversity among accidents a priori from the diversity of the parts of substance from which the accidents flow, and gives three distinctions.

The first, with its subdivisions, is as follows. Some accidents principally follow form, others principally follow matter. Among the accidents following form, some communicate with matter, while others are separate from matter. Among the accidents following matter, some follow it in relation to a general form, and others in relation to a special form.

The reason for the first division is that, since everything acts through that by which it is in act, and some species is always thought to move and act, as is said in Physics III, text XVII, operations and operative powers must follow form. Likewise, since everything undergoes and is changed by reason of matter, several accidents must follow it, such as those which inhere because of matter’s different complexion and subject it to motion, and so on. He added “principally” in the first division to distinguish it from “totally.” For no accident belongs to form alone or matter alone, but all belong to the composite. Indeed, even for intellection, not only the soul concurs but the whole composite of matter and form: it is Socrates who first understands. The sense of the division, then, is that some accidents follow form not as their total cause but as their principal cause, and some similarly follow matter as their principal but not total cause. Since the cause of all accidents is what truly is, namely complete substance, the cause of all is the composite of matter and form; but for some the principal root is form, and for others the principal root is matter. Just as in artificial things one feature belongs to the composite by reason of form and another by reason of matter—cutting belongs to a saw by reason of its form, hardness by reason of its matter—so in natural things something arises in the composite by reason of form and something by reason of matter. Thus in Socrates sensing and understanding are by reason of form, while masculinity is by reason of matter. The rule for discerning accidents following form from those following matter will be assigned below.

Some form is found whose being does not depend on matter, such as the intellectual soul. Matter, however, has being only through form. Hence among the accidents which follow form there is something which has no communication with matter, such as understanding, which is not through a bodily organ, as the Philosopher proves in On the Soul III. Some consequences of form, however, have communication with matter, such as sensing; but no accident follows matter without communication with form.

Here the first subdivision is set down together with its cause. Since the proper powers, properties, and operations of forms must be proportioned to the forms themselves, if the essence of the form depends on matter, its power and operation, since they are not the form itself from which they flow but are more perfect, must depend on matter. If the essence of the form is independent of matter, it must have some power independent of matter; otherwise nature would have made a form independent for no purpose. It would have made a nature elevated above matter in such a way that it could not act and consequently could not attain its proper end; for everything exists for the sake of its operation, as is said in On the Heavens II, text XVII. Since, therefore, there are two kinds of substantial forms—those dependent on matter, such as all material forms, and those independent of it, such as the human soul—there are two kinds of accidents following form.

Some accidents flow from a form dependent on matter, and they flow from it in such a way that they are nevertheless received subjectively in the composite; for this reason they are said to have communication with matter, such as sensing, vegetating, and the like.

Others flow from a form independent of matter as such. They flow from the form itself in such a way that they are received subjectively in the form alone; for this reason they are said not to have communication with matter, such as intellect and will, understanding, willing, and the like.

Nor should you think that we now contradict what was said above through forgetfulness. Both are true: namely, that every accident belongs to the composite, as we said above, and that some accident belongs to form alone, as we are now saying. For an accident’s belonging to something can be understood in two ways. In one way, as belonging to a complete elicitive and receptive principle; in another way, as belonging to a suppositum. In this second way every accident belongs to the composite whose being and becoming it is; hence the soul does not understand as a suppositum which acts, but Socrates does so through the soul. In the first way, however, some accident belongs to the soul itself and some to the composite. For the intellectual power is not subjectively in any bodily part composed of matter and form, but is subjectively in the essence of the soul alone; hence in On the Soul III, text IV, it is said that the intellect is the act of no body. The sensitive powers, however, are not subjectively in the soul alone, but in determinate bodily parts composed of matter and substantial form. Likewise, the complete elicitive principle of sensation is not the soul’s power alone, but the composite of bodily organ and power of the soul. The complete elicitive principle of intellection, however, is the intellectual power alone. Since an immanent operation is subjectively in its elicitive principle, understanding will be in the intellect alone as in its subject. For this reason St. Thomas elsewhere says that the soul understands as the eye sees: it sees as a complete elicitive principle, for “eye” names the composite of bodily organ and power of the soul. These statements do not contradict one another, then: every accident belongs to the composite as suppositum, and some accident belongs to form alone as complete elicitive and receptive principle. Although the entire discussion concerns accidents of material substances, it nevertheless indicates from these things the nature of accidents following a form independent of matter.

And note that before the subdivision of the other member is given, the text assigns the reason why there is not, for accidents following matter, a subdivision like that made for those following form—namely, that among accidents following matter some communicate with form and some do not. The reason is that there is not a twofold matter, one dependent on form and the other not, as there is a twofold form; for no matter can exist without form.

Nevertheless, among the accidents that follow matter there is a certain diversity. Some accidents follow matter according to the order which it has to a special form, such as masculinity and femininity in animals, whose diversity is reduced to matter, as is said in Metaphysics X. Hence, when the animal’s form is removed, these accidents remain only equivocally. Others follow matter according to the order which it has to a general form; and therefore, when the special form is removed, they still remain in it, as the blackness of skin remains in an Ethiopian because of the mixture of the elements and not because of the soul’s account, and therefore remains in him after death.

Here the division of the other member is set down as follows: Among the accidents following matter, some follow it in relation to a general form, and some in relation to a special form. Those accidents are said to follow matter in relation to a general form which belong to an individual of a higher genus by reason more of its matter than of its form. Thus this mixed body has blackness of skin not by reason of the form of the mixed body, but because its matter has undergone such a condition—for example, in a climate where the sun’s heat abounds. Those accidents, however, are said to follow matter in relation to a special form which belong to an individual of a lower genus or species more by reason of matter than of form. Thus this animal is masculine not principally by reason of its soul, but because such a property accompanied matter disposed for the soul—for example, because the matter was not fully subject to the dominance of vigorous semen. The sign that accidents are related in this way, namely that they follow matter according as it regards a form of a higher or lower genus, is that some of them of the same account remain in the corrupted composite, while others remain only equivocally. For the blackness of a living and dead human being is of the same account, but masculinity is not. The only cause of this is that masculinity follows the animal by reason of its proper matter; and therefore, when the animal is corrupted and only equivocally remains, masculinity, whose account includes animal, must remain equivocally. But whiteness, because it follows the matter of the mixed body remaining in the corpse according to the same definition, remains not equivocally.

Whether the same accidents numerically exist in what is generated and what is corrupted. The opinion of certain Averroists. In De substantia orbis, ch. 1, and Physics I, text 66.

Concerning what is said here, a doubt arose: whether the blackness of the skin in a living and a dead Ethiopian is one and the same numerically; and universally, whether the accident in what is generated and what is corrupted is the same numerically. Three things must be done in this doubt: first, the opinion of certain men will be recited; second, the opinion of St. Thomas will be set forth; third, the objections will be answered.

Regarding the first, some think that accidents common to what is generated and what is corrupted are numerically the same in both. Among them are certain men who, relying on some words of Averroes, express their view with this distinction: accidents common to what is generated and corrupted have two modes of being, namely, determinate and indeterminate. They call indeterminate accidents the essences of accidents without limitation to this or that degree. They call determinate accidents the essences of accidents limited to this or that degree. They hold that indeterminate accidents are numerically the same in what is generated and corrupted, but not determinate ones. Thus, just as the indeterminate quantity common to things is explicitly held by the Commentator to be the same in all, so too the common indeterminate color; the same applies in air and fire.

This opinion is confirmed by authorities and arguments. Aristotle, in Generation I, text 23, saying, “But if any things remain in what is generated and what is corrupted, for example in air and water, if both are transparent or moist, etc.,” shows that it is not unreasonable for some identical accident to be in what is generated and what is corrupted. In Generation II, text 25, he expressly holds that transition is easier in things having a common element, because it is easier to corrupt one than two. Averroes too, in his book On the Substance of the Orb, near the beginning, says that not only indeterminate dimensions, which he calls simple, remain the same in what is generated, but universally all qualities common to what is generated and corrupted.

The first argument for this is: if the qualities disposing the matter of the thing to be corrupted for a new form are corrupted, what draws out the form to be generated? It cannot be said that this is an external agent, because it can do this only through intermediate qualities introduced into matter. But the opponent says that those qualities are corrupted before the induction of the form. Therefore nothing remains to draw out the form, which is impossible.

Moreover, with what are the common qualities corrupted, since no contrary appears? And it is pointless to judge that things are corrupted at an instant at which the same thing must be generated.

Moreover, if the figure of a corpse, the arrangement of its organs, the scar, and whatever is of this kind do not remain the same, with what are they generated? Since it cannot be said that they are generated by way of consequence, there must be no generator. That they are not generated by way of consequence is proved as follows. Some accidents are generated consecutively because what gives the form gives what follows upon the form. But these accidents oppose the form more than they follow it; a sign is that, under the form of a corpse, they tend toward corruption. And so much for the first point.

CONCLUSION

The accidents in what is generated and what is corrupted are not numerically the same.

Regarding the second, one must know that the Thomists’ opinion is that no accident is numerically the same in what is generated and what is corrupted. This follows necessarily from our principles. For if no accident is subjectively in matter, and there is only one substantial form in a composite, it is impossible for the same accident to remain numerically the same. It would migrate from subject to subject and would be both the same and not the same. I will not now bring forward arguments for this conclusion, since effective proof requires proving that principle, namely, that there is only one substantial form in a composite. But I will explain how this is possible and how our position is to be defended against its opponents.

An accident is corrupted in four ways. First, through an alteration opposed to it by its contrary, as cold is corrupted by heat. Second, through the absence of a preserving agent, as light in air ceases when the sun withdraws. Third, through the corruption of its subject, as risibility is corrupted when a man dies. Fourth, through the corruption of its terminus, as likeness ceases when the like thing is destroyed. And since one of a pair of opposites is spoken of in as many ways as the other, an accident is generated in four ways as well. First, by an agent like itself through transmutation, as water is heated by hot fire. Second, through the presence of an agent in becoming and in being, as light in air comes from the sun when present. Third, through the generation of the subject, as the laughable is generated when a man is generated. Fourth, through the generation of the terminus, as, when only Socrates exists as white, likeness immediately arises in Socrates upon the generation of another white thing.

Although an accident can be corrupted in its whole range in all these ways, only the third applies to all accidents. It is common to all accidents that they are corrupted when their subject is corrupted, since the being of an accident is to be in something. Therefore the corruption of the subject is a sufficient cause of the corruption of accidents. Thus, when fire is made from air, although the heat of the air need not be corrupted but rather intensified, because the air that is its subject is corrupted, the heat too must be corrupted without a contrary, solely through the failure of its subject. Hence it is evident how the arguments commit the fallacy of consequent when they infer that common qualities and dispositions made for introducing a form remain because they lack a contrary that corrupts them.

It should be noted that when an accident is generated through the generation of its subject, or corrupted through the corruption of its subject, then, since the same action terminates both in the subject per se and in the accident consecutively, no other generator or corrupter need be sought besides the generator or corrupter of the subject. The agent is the same, making both simultaneously and by the same operation. Thus, when fire generates fire from air by altering the air, at the end of the alteration it corrupts the air per se and, consecutively, the introduced heat and all the accidents subjectively in the air with that necessary consequence; for an accident cannot remain without its proper subject. In the same instant it generates fire per se and, consecutively and without another intermediate alteration, heat like the heat existing before that instant. The same judgment applies to quantity, figure, and other dispositions and similar accidents in what is generated and corrupted: all these are produced concomitantly, and therefore no generator need be sought except the generator of the subject. Having considered the foregoing, you will see that what is like is sometimes concomitantly and accidentally corrupted by what is like, and conversely the accident itself can be concomitantly and accidentally generated by what is unlike. Therefore, whenever Aristotle says that the same things remain in what is generated and corrupted, he means the same in species, not numerically, and accidentally. Numerical unity varies not through the power of generation but through the corruption of the subject. The easier transition in things having a common element arises not from numerical identity of the common accident, but from its non-repugnance in acting or undergoing, and from the greater similarity of the substantial forms from which similar qualities flow; for nature is known through its effects. Averroes, if he is to be preserved, should be glossed in the same way.

The arguments for the contrary opinion are answered as follows. To the first: what draws out the form in the final instant is an external generator, not through an action elicited in that instant, but at the term of the action, touching the bare essence of matter. Thus, when it is said that an external agent cannot draw out the form except through intermediate qualities introduced, this is true while it is acting, but not when it is at the term of its action. It is enough, and is required, that it have altered matter for its stripping and disposition.

To the second: common qualities and the like are corrupted accidentally through the corruption of the subject by the corrupter that corrupts the subject per se. Nor is their first non-being and the first being of similar qualities in the same instant pointless; it occurs necessarily, by the necessity of matter.

To the third: figure, scar, and the like are produced consecutively and accidentally by the generator of their subject, namely, the corpse. It is not true that only those accidents are generated consecutively which follow the form. Many accidents follow the composite by the necessity of matter; although not incompatible, they are in some way opposed to the form itself, as is clear in itself. Thus I say that figure and the like follow the corpse by the necessity of matter: a natural agent cannot so quickly and through so many transmutations completely corrupt deeply rooted dispositions, and therefore similar dispositions follow. Because they do not serve the form of what is generated, corruption is hastened.

Since each thing is individuated by matter and placed in a genus or species by its form, the accidents that follow matter are accidents of the individual, according to which individuals of the same species also differ from one another. Accidents that follow form are proper passions of a genus or species, and so are found in all participants in the nature of that genus or species. Thus risibility follows form in man, because laughter arises from some apprehension of the human soul.

Here a second division of accidents is set down: some are accidents of the individual, others accidents of the genus or species.

Two differences between these are given. First, individual accidents follow the composite principally by reason of matter, whereas species or genus accidents follow the composite by reason of form. Second, individual accidents are those according to which particulars of the same species differ; species or genus accidents are necessarily common to all individuals of that species or genus. Male and female, for example, are individual accidents: they follow matter, and Socrates and Bertha differ according to them. Risibility is a specific accident: it follows intellectual apprehension and necessarily belongs to all human beings. The root of the first difference is also assigned: matter is the principle of individuation, while form places a thing in a genus or species. Since matter causes individual being as such, it is also the root of accidents following individual being; hence individual accidents follow matter. Since form is the principle of generic and specific being, it must also cause the properties and accidents following species or genus; thus these follow form. The reason for the second difference is that, since all things contained under a specific or generic form agree in it, its properties must also be common to all. Since individuals differ according to matter, material accidents must be those according to which the particulars themselves differ, so that effects correspond proportionately to their proper causes.

Two doubts arise here concerning the text. The first is how it is true that accidents following matter are those according to which individuals in the same species differ, since quantity follows matter and nevertheless is common to all individuals of body and lower things.

The second doubt is how it is verified that accidents following matter are not passions of a genus or species, since male and female follow matter and yet are passions of animal; hence animal is placed in their definition as the subject is in the definition of a passion, as is held in Metaphysics X, text 15. Similarly, quantity seems to be a passion of body in the category of substance, and yet follows matter.

For the first point, know that the words “accidents following matter are those according to which individuals differ” are not to be understood uniformly but disformly. Individuals differ according to material accidents in two ways: either one has one accident and the other another, or both have the same accident but in different ways. Thus Socrates and Bertha differ according to male and female because he has masculinity and she femininity. They also differ according to their quantities, not because he is quantified and she is not, but because they are not quantified in the same way; two quantities wholly alike are never found, since they must differ in their proper positions. Therefore, although quantity is common to all individuals, because it belongs to them non-uniformly it is that according to which they differ in the second way, and this suffices.

For the second, note that passions of genera are of two kinds. Some belong to them by reason of their generic form, others by reason of their matter. Those following form are here called passions of genera, not those following their matter, because generic nature is such through its form, not its matter. Animal is animal through its form, not its matter. Thus, in the case at hand, sensibility is a passion of animal by reason of form, while masculinity or femininity is one by reason of matter. Aristotle in the Metaphysics and St. Thomas here, moved by different considerations, spoke differently: because it is a passion of animal by reason of matter, it is called a passion there; because it is not so by reason of form, it is not called a passion here.

The same must be said of quantity, since it follows body by reason of matter. It follows body according to its being potentially divisible, which is nothing but matter, as the indivisibility of immaterial things shows. Note that this second division of accidents does not differ from the first in its dividing members: the members of both are the same, but according to a different account. The first division is taken according to their first roots, matter and form; this one according to the subjects to which they are appropriated, namely genus, species, and individual.

It must also be known that sometimes accidents are caused by essential principles according to perfect act, as heat in fire, which is always actually hot. Sometimes they are caused only according to aptitude, but receive completion from an external agent, as transparency in air, which is completed by an externally lucid body. In such cases the aptitude is an inseparable accident, but the completion that comes from a principle outside the essence of the thing, or that does not enter into its constitution, is separable, as motion and the like.

Here a third division of accidents is set down: some are caused from the essential principles of the subject according to perfect act, others according to aptitude alone. He calls those caused according to perfect act from essential principles the accidents that flow in the subject according to their actualities from its intrinsic principles, as heat in fire. He says those are caused according to imperfect act, or aptitude alone, which flow from the essential principles of the subject not according to their actualities but according to certain beginnings, as upward motion in fire is caused from its principles according to its beginning, namely lightness. They differ because the first are inseparable from their subjects both according to their aptitudes and according to themselves, whereas the second are separable in themselves but inseparable according to their aptitudes. Neither the aptitude for heat nor heat itself can be separated from fire while fire remains; upward motion, however, is not always in fire, while the aptitude for upward motion, namely lightness, is inseparable from it. The cause is that in the first cases the actuality of the accident itself flows solely from essential principles; in the second only the aptitude flows from them. The actuality is awaited from something else extrinsically concurrent, either by acting or by not preventing, as in upward motion, which is present in fire only when an external concurrence removes what prevents it. Transparency is not actually in air without an external illuminator; for light is the act of the transparent in act, as is said in On the Soul II, text 69.

I derive a deeper cause of this division from the first article of the tenth question of the second book, reply to objection 2: some accidents arise inseparably from essential principles according to complete act, while others arise separably according to complete act and inseparably according to aptitude, because the former follow the actuality of the thing, the latter its potentiality. I understand this as follows: each thing acts according as it is in act, but undergoes according as it is in potency. From sufficient actuality of the thing it follows that it produce the accident complete in itself; conversely, from insufficient actuality, and consequently from potentiality, from which all sufficiency proceeds, it follows that the thing has the accident only according to aptitude in itself and awaits its actuality from another, or that the accident is separable according to actuality, which is the same thing.

Moreover, since being and goodness follow actuality, while non-being and evil follow potency, from the actuality of a thing there must proceed a perfect accident, inseparable according to act and aptitude; conversely, from the potentiality of the thing there must proceed incompletion of the accident and its separability according to act. Separability itself is a kind of non-being, since it is nothing other than the negation that the necessary consequence of its complete being follows upon the being of the subject. Understand that aptitude comes from the actuality of the subject, while separability of the accident according to its actuality comes from potentiality.

It should be observed that St. Thomas did not simply place among the accidents flowing from essential principles the passions that express aptitude, but rather the acts of those passions and aptitudes, which he called aptitudes according to incomplete being. He did this because aptitude in itself does not have the character of something produced or producible per se. No natural producer intends aptitude, but the act of aptitude; risibility is not needed except that one laugh, and so risibility is a certain beginning of laughter. Therefore aptitude is not simply placed among the effects of essential principles, but the act is, because it is not aptitude itself but its act that productive principles intend. Since aptitude is nothing other than a certain beginning, and a beginning is imperfect act, accidents according to incomplete act are called aptitudes.

Before we end the treatment of the diversity of accidents, it is asked whether every accident has some proper subject, or whether some accidents are so common that they belong properly to no one.

The reason for doubting is that, if every accident is proper to something, since what is proper belongs to everything, only that thing, and always, no accident will be separable from what it is in. It would belong only and always to its proper subject.

Moreover, it would follow that the corruption of any accident would always accompany the corruption of substance, as, when the laughable is corrupted, man is corrupted. The consequence is clear: when what is proper is corrupted, that of which it is proper must be corrupted, otherwise it would not belong to it always. Yet we experience this to be false, as is clear with common accidents and second acts.

On the contrary, since every accident is definable and its subject, of which it is predicated per se, enters its definition, as is clear in Posterior Analytics I and Metaphysics II, every accident must have a proper subject and a subject per se; for “per se” presupposes what belongs to all, always, and necessarily.

For clarity concerning this doubt, one must know that, according to St. Thomas, Questions on the Virtues, question 3, article 3, the subject has three relations to its proper accident: that of sustaining to what is sustained, potency to act, and principle to what is principled. Thus heat in fire has no being unless it is sustained in fire, is its accidental form, and arises from it insofar as it participates in these conditions. It can therefore be called the subject of the accident; insofar as it departs from these relations, the subject of the accident can be denied. Because of the defect of the first, which is the principal relation, Posterior Analytics I says that no accident is subjectively in another accident: no accident can sustain another, but only substance, which is being through itself, provides other things with support for being. Since one accident can nevertheless be compared with another as potency to act, and sometimes as proximate principle to what is principled, one accident is also conceded to be the subject of another. Thus surface is called the subject of color because it is in potency with respect to color, and sweetness is said to be in the hot and moist because it is caused by the hot and moist. The doubt raised can therefore have four meanings. First, it can ask whether every accident has a proper subject as sustainer; second, whether it has a proper subject as potency; third, whether it has a proper subject as principle; fourth, whether it has a proper subject as sustainer, potency, and principle together.

If the question is taken in the first sense, the answer is negative: not every accident has a proper subject in the character of a sustainer, as the arguments first introduced prove. Many accidents claim no one proper sustainer for themselves but are commonly in many things, as their separation shows; they are separated from the sustaining substance while it naturally remains. This cannot be said of proper accidents. The same substance sustains contraries without its own change, as is said in the Categories.

If the doubt is taken in the second sense, the answer is affirmative: every accident has a proper subject in the character of its proper potency, because every act regards a proper potency. Just as act regards potency, so this act regards this potency, and a specific act a specific potency. Every accident is an act; therefore every accident has a proper potency of which it is the act. Hence Physics III, text 10, says that potency for infirmity differs from potency for health because health differs from infirmity; and through a long argument in Metaphysics XII it is proved that the principles of the Categories are proportionately the same, since a proper potency corresponds to every act.

If the inquiry is made in the third sense, the answer is negative: not every accident has some proper subject in the character of its proper principle. For to have a proper subject as principle includes the flowing of that accident from such a subject in the genus of efficient cause, in the way that, among two effects ordered to one another, the prior is the efficient cause of what necessarily follows its production, whether that subject is receptive of the accident as that by which, or as that which. It is clear that not every accident flows effectively from its receptive subject; in many cases the receptive subject is purely passive, as when the species of a sensible thing is received in the medium or in the sense.

If the question is understood in the fourth way, what must be said is clear: one must answer negatively.

It should be noted that what we have said must be understood of accidents—acts and aptitudes taken separately. If we speak of accidents as St. Thomas speaks in the text, without judging the actualities of accidents separately from their aptitudes, I would say that every accident, according to its radical aptitude, has a proper subject in the character of sustainer, potency, and principle, though not according to its actuality. The aptitude for such an accident flows mediately or immediately from such a substantial grade, and consequently is sustained subjectively, mediately or immediately, in such a grade. For example, although light according to its actuality and substance is from outside and is a separable accident, according to its beginning or radical aptitude—namely, transparency—it is inseparable and flows from a certain substantial grade common to higher and lower things. Likewise, although sitting is an accident, according to its aptitude it is properly, though accidentally, the property of a certain being and is not naturally suited to belong except to such an entity, for example such an animal. The aptitude for sitting flows from its principles. Similarly, although seeing is a separable accident, the radical aptitude for seeing cannot be separated from such an animal.

From this it is clear how the arguments brought for both sides conclude truly in different ways. Speaking of accidents according to their essences and actualities, the conclusion of the first arguments is granted, taking subject in the character of sustainer and principle.

In the character of potency, the conclusion is false, as was said. Nor does the proof applied against this interpretation have force. When it is said that what is proper belongs only, to all, and always, this is understood of the proper not according to its actuality but according to its aptitude. Likewise, when it is said that when what is proper is corrupted its subject ceases, this is understood if it is corrupted according to aptitude, not according to act, universally speaking. Or one may say that inseparability and the like do not belong to an accident as it regards a subject in the character of its proper potency, but as sustainer and principle. Speaking of accidents according to their aptitudes, it is clear how the arguments fail. I say that no accident is separable according to at least its radical aptitude, but is necessarily coeval with its subject; and when an accident is corrupted according to such aptitude, the subject must be corrupted. The contrary argument concludes that every accident has a subject of which it is predicated per se, whether in itself or according to its aptitude. Since an act belongs to that to which its potency belongs, as is said in Sleep and Waking, the same subject enters the definition of the accident according to aptitude and act: man must be placed not only in the definition of the laughable but also of laughter. These two therefore stand together: according to its actuality an accident has no proper subject to which it belongs universally, only, and always, yet it has a proper subject through which it must be defined, because for this it suffices that according to its aptitude it be predicated per se of that subject. For the first, it suffices that the accident in itself not be predicated per se of the subject.

It must be known that in accidents genus, difference, and species are taken in another way than in substances. In substances, matter and substantial form produce a per se one, a nature resulting from their conjunction, properly placed in the category of substance. Thus concrete names signifying the composite, such as man or animal, are properly genera or species; form and matter enter only reductively as principles. But accident and subject do not make a per se one, nor does their conjunction yield a nature to which genus or species can belong. Therefore concrete accident-names such as white or musical are placed in a category only reductively; properly, only the abstracts whiteness and music are placed there.

In this third part of the chapter it is determined how accidents relate to logical intentions: first, how they relate to being in a category; then, from where genus and difference are taken in them. Regarding the first, two conclusions are given: accidents in the concrete are not properly in a category, and accidents in the abstract are properly in a category.

For clarity, accidents have one mode of being, namely, being in another; they exist only insofar as they are in something. They have two modes of being understood, because the intellect is naturally able to divide things united in reality. Sometimes they are understood together with their subject, in which they inhere, and are understood in the mode of an accident, because an accident’s being is being in another. Sometimes they are understood alone, without understanding with them the subject in which they really inhere; then they are understood in the mode of substance, because being through itself, that is, alone, belongs only to substance, while accidents always need a companion. Since the mode of signifying is founded not on the mode of being but on the mode of understanding, they consequently have two modes of signifying. Sometimes they are signified by consignifying the subject, and then in the mode of an accident; these are signified in the concrete, such as white and black. Sometimes they are signified alone, without consignifying the subject; then in the mode of substance, such as whiteness and blackness. In accidents, abstract and concrete differ in mode of signifying—consignifying the subject or not—yet agree in signifying the accidental form itself. White signifies pure quality, as Aristotle says in the Categories, just as whiteness does; but white signifies whiteness in a subject, whereas whiteness signifies it without the subject. Since concrete accidents signify the whole joined thing, such as white signifying whiteness in a subject, and this joined thing is not one per se but one and being accidentally, while what is placed in a category must signify one and being per se, since the categories divide being per se, concrete accidents are not properly placed in a category. This is the argument by which the first conclusion is proved in the text: no name signifying being and unity accidentally is properly in a category; an accidental concrete signifies one and being accidentally; therefore an accidental concrete name is not properly and per se placed in a category. The difference between accidental and substantial concrete is added to clarify the minor: substantial concrete signifies a composite of matter and form, which is one per se and is therefore placed in a category as genus or species; accidental concrete signifies a composite of subject and accident, which is one accidentally. From accident and subject there is only one accidentally, as is said in Metaphysics VII, and therefore it should be placed in a category only reductively, in the way an impure thing is reduced to the purity of its nature.

Thus the second conclusion remains true: accidents in the abstract receive the predication of species and genus in a category; otherwise accidents would be wholly excluded from the categories.

When you hear that the abstract signifies only the form, do not think this means that the abstract wholly excludes the subject of the form. That is false. It means that, through its mode of signifying—the only respect in which it differs from the concrete—it does not include the subject principally, but secondarily and consequently. This can be shown from the agreement and difference between them in their mode of signifying. Both abstract and concrete signify two things: the that which and the whereby, or subject and form. A definition and what is defined signify the same thing, though in different ways. Thus we call snubness the curvature of the nose, and snub a curved nose. That this belongs to the mode of signifying is clear because both abstract and concrete signify pure form, as Aristotle testifies in the Categories. They differ in that the concrete, by its mode of signifying, principally signifies the subject and secondarily the form; the abstract principally signifies the form and consequently the subject.

Observe that subject and form stand in the opposite order in the signification of a concrete name and in its mode of signifying. In signification the concrete first imports the form, and the subject only consequently through the copula. In its mode of signifying it first imports the subject and consequently the form. A sign is that in the definition of the concrete the subject is expressed first as genus, the first part of the defined thing, and the form is placed second as difference: snub is a curved nose. The abstract imports the form first both in signification and in mode of signifying, while the subject is secondary and consequent. In its definition the form is first expressed as genus and the subject second as difference: snubness is the curvature of the nose. This difference arises because the concrete signifies a relation between subject and form beginning from the subject and terminating in the form. The abstract signifies a relation between form and subject beginning from the form and terminating in the subject, as the examples show. The cause is that concrete names were invented to signify composites, and composition arises from the subject. Abstract names were invented to signify forms that are simple as found by us but from which denomination is derived to subjects. Hence concretes sound like composites, while abstracts sound like forms nevertheless falling upon subjects. It was not therefore said that the abstract signifies only the form because it in no way joins the subject, but because, by its mode of signifying, it does not sound as a composite or principally import the subject as the concrete does; it signifies the subject only extrinsically, as the terminus of the relation of the signified form.