Cursus Philosophicus Thomisticus, Secunda Pars Artis Logicae

SUBSTANCE here is not taken to mean the quiddity or essence of a thing. For in that sense it is not a special category, but a general notion of any quiddity or essence; and substance taken in this way is opposed only to an accidental predicate, not to a predicamental accident, since this accident too has its own quiddity. Hence substance is taken here to mean a being existing in itself, that is, opposed to an accident inhering or existing in another. This property of existing in itself is understood either in an absolute consideration and in relation to itself; in this sense it is called subsistent, as needing nothing else to support it, but standing in itself; or it is understood in relation to others, insofar as it supports them in being, and in this sense it is called not only subsistent but also substant. For just as shining differs from illuminating, although the latter proceeds from the former, so being in oneself without needing support from another is a different consideration from supporting others and giving them being.

In this way St. Thomas explained the notion of this first category in Sentences I, dist. 23, q. 1, art. 1.¹ He says that “being expresses what is common to all genera, but to subsist and to underlie express what is proper to the first category, according to two features belonging to it: namely, that it be a complete being in itself, and, further, that it underlie all other things, namely accidents, which have being from substance.” Thus St. Thomas. Here he clearly explains that the constitution of substance as the first category is taken in relation to these two acts, subsisting and underlying. Subsisting is spoken of in relation to oneself and to one’s own being; underlying is spoken of in relation to the things one supports, such as accidents. The expression being in itself can be taken positively or negatively: positively, for that perfection of being which excludes dependence on another; negatively, for the very negation of dependence and communication to another. The expression in itself can also be taken in several ways, as we shall say in the third conclusion. We must therefore explain how in itself is taken in the constitution of substance, and to which property it relates first, subsisting or underlying.

I SAY, THEN, FIRST: The definition or description of substance as the first category—for strictly speaking it is not defined, since it is a highest genus not composed of genus and difference—is “a being existing in itself.”

So St. Thomas, opusc. 48, On the Categories, chapter 2.² He explains the same point in Sentences IV, dist. 12, q. 1, art. 1, question 1, ad 2,³ where he teaches that this definition is to be understood in the sense that substance is a thing to which being in itself, or existing in itself, is due, just as an accident is a being to which being in another is due. For actually being in itself or in another is not the very quiddity of substance or accident, since being or existing is not an intrinsic predicate in any created quiddity. And quantity in the Eucharist is a true accident and does not actually exist in another, but only has an aptitude to do so. Substance is defined more by reference to existing in itself, or subsisting, than by reference to underlying, because subsisting belongs to it first, as relating to itself, before underlying, which relates to supporting other things.

I SAY, SECOND: The self-subsistence of substance does not consist in negation alone, but in a positive notion.

The REASON is most evident: being in itself is nobler and more perfect than being in another. But being in another is a positive mode of being, namely, by inherence and union with another. Therefore, being in itself is not a pure negation, but something positive. For a mere negation and exclusion of something positive does not constitute something more perfect, just as the mere negation of a brute does not constitute the perfection of a human being. Finally, this negation would have to be founded on something positive; otherwise it would be pure nothing and would not constitute a positive being such as substance. But it is not founded on being in general, since then it would belong to every being; therefore, it is founded on something determinate and distinct from accident, and this is substance.

When St. Thomas says in Summa contra gentiles I, chapter 25, that the expression in itself seems to imply nothing but negation, which cannot constitute a nature or the notion of a genus, some have taken occasion to attribute to St. Thomas the view that self-subsistence in substance signifies mere negation. The holy Doctor does not affirm that; he says only that the particle in itself does not constitute a genus. How substance is constituted by the notion of being in itself, St. Thomas immediately explains in these words: “Therefore, the notion of substance must be understood in this way: substance is a thing to which it belongs not to be in a subject. The name ‘thing’ is imposed from quiddity, just as the name ‘being’ is imposed from being. Thus, the notion of substance includes that it has a quiddity to which it belongs not to be in another.” What in itself implies by the imposition of its signification is one thing; what it implies insofar as it explains the constitutive quiddity of substance is another. In the first sense, it requires nothing more than signifying negation of being in another. In the second, it expresses a positive notion of being, though with the perfection of also having a negation of being in another.

I SAY, THIRD: The expression in itself can be opposed to a being per accidens; to a being inhering in another, which is an accident; to a being existing in another as a part in a whole; and to a being existing in another without being incommunicable or ultimately terminated, as an integral human nature is in a supposit.

In the first sense, being in itself does not belong only to this category of substance, but to any being that is not a being per accidens; for quantity too is a being in itself in this sense. In the second sense, it belongs to substance, both complete and incomplete, as St. Thomas observes in opusc. 42, chapter 10,⁴ and opusc. 48, treatise 2, On Substance, chapter 2;⁵ for even a part of substance is not an accident. In the third sense, it belongs to predicamental substance, which expresses the whole quiddity and complete nature as a nature, though not as a supposit, as with humanity. In the fourth sense, it belongs to a supposit. See St. Thomas, opusc. 48 cited above,⁶ where he says that “composite substance can be understood in two ways: as nature and as supposit.… For although humanity is called a form, it is nevertheless composed of matter and form, since humanity expresses soul and body. Yet humanity, or any nature, expresses a substantial and natural form in such a way that, by its principal signification, it abstracts from everything other than the aforesaid form and matter. This is not so with a supposit, which by its principal signification expresses something having humanity.… And because that which has humanity can be a nonhuman supposit, as is clear in the humanity of Christ, which is suppositated by a divine supposit, or can have certain other things, such as accidents, from which humanity wholly abstracts, supposit and nature differ in creatures.” Thus St. Thomas. Indeed, being in itself as opposed to an accident inhering is clearly found in every substance, complete or incomplete, just as it is distinguished from every accident. But if the substance is complete, it must also exclude the notion of a part, since it is a whole and complete. Subsistence and existence, however, belong to the mode of being, and underlying belongs to the support of other things; all of this is extrinsic to the nature and quiddity itself. Therefore, it does not constitute the nature of substance in act, but gives it only an aptitude for this, just as an accident has an aptitude for inhering and existing in another.

I SAY, FOURTH: Subsistence, supposit, hypostasis, or person expresses not an intrinsic and essential term of substance, as though it were a predicate constituting it, but an extrinsic term whose role is to render a nature ultimately incommunicable to another.

For the distinction among these names, see St. Thomas in the cited Sentences I, dist. 23.⁷ Subsistence, supposit, and hypostasis are commonly said of substance in any nature; person, however, is said only of an intellectual nature. That it does not belong to the intrinsic term is taught by the mystery of the Incarnation, in which the whole quiddity of human nature is found without its own subsistence. Therefore, subsistence is not a quidditative predicate. Yet it is a term, because it renders a nature ultimately terminated and incommunicable and thus receptive of accidents, while the nature of an accident remains unmixed with the nature of substance. This is a sign that accidents are not joined immediately to a nature, but to some thing of that nature, which is the supposit and is distinct from the nature.

What this subsistence is—whether a thing or a mode distinct from the nature—is not for the present place to explain; that belongs to metaphysics. See Cajetan, Summa theologiae III, q. 2, art. 2. But if it is distinct from the nature, how is it predicated of the nature? We reply that it is predicated of the nature concretely, as existence and other accidental predicates are: one says “an existing and subsistent man,” or “a person,” but one does not say “subsistence” or “existence,” nor is humanity called a person.

Some say here that humanity taken physically is distinct from subsistence and expresses only a nature stripped of subsistence, but that, taken metaphysically, it expresses a nature abstracted from individuating differences; conversely, the concrete “man,” taken physically, expresses a nature with a supposit, while taken metaphysically it expresses a nature while connoting differences. But this is an abuse of terms. For even humanity considered metaphysically is signified in the manner of a form, not in the manner of a whole; it signifies the abstract of the name “man,” and only that by which man is man. Therefore, it abstracts from individuating differences in such a way that it is not predicable of individuals. This can arise only because it is signified as a part, and therefore in relation to some whole. But the whole is the supposit. Therefore, even humanity taken metaphysically is signified as stripped of supposit and subsistence, although it is true that, considered physically, it is taken as singular in the way in which the Divine Word assumed it. Metaphysically, however, it can also be considered in common. But it is not clear how “man,” considered concretely and metaphysically, connotes lower differences, since it abstracts from them, as a universal abstracts from contracting differences.

I SAY, LAST: When the definition of substance says “a being existing in itself,” the word existing or being is taken for existence itself, by which a thing is outside its causes; this is not quidditative being.

THE REASON IS that the difference between substance and accident is taken from the different order and mode in which each requires to exist outside its causes: an accident requires existence with dependence through inherence, while substance requires it without such dependence. We shall speak in physics of how this existence is distinct from the nature and quiddity of each created thing.⁸ For now, it suffices to hear St. Thomas in opusc. 48, treatise 2, chapter 2, On Substance,⁹ where he says that “in creatures, the being of essence and the being of actual existence differ really, as two distinct things. This is clear as follows: what is outside the essence of something”—understand this physically, so that there is no objection concerning a difference that is outside the concept of a genus metaphysically speaking, yet does not really differ from it—“really differs from it. But the being of actual existence is outside the definition, because the definition posits only genus and difference and makes no mention of whether the defined thing exists or does not exist.” Thus St. Thomas.

YOU WILL OBJECT: Substance must be constituted by something added to being; it is not positive, therefore it is negative. The minor premise is clear: it is not something positive in reason, because what is constituted by it is a real being; nor is it something really positive, because then it would add nothing to being, since being itself is included in every being. Indeed, it would be redundant to say, “Substance is a being in itself,” that is, “a real being is a real being.” Therefore, it implies something negative.

Second: being in itself also belongs to something constituted from an accident and a subject—for example, something white—so it does not belong only to substance. Being in itself without a subject also belongs to an accident separated in the Eucharist. Therefore, that definition does not express the adequate notion of substance.

Finally, to underlie is what most properly makes substance substance. For Aristotle says¹⁰ that first substances are substances most of all because they underlie most of all. Therefore, underlying is the proper notion of substance.

THE REPLY IS to the first objection that substance is constituted by a positive mode of being in itself, which adds to being not a new and distinct reality but a new mode. As regards entity, this mode is contained in being itself, but it is expressed in a new way. For this is the general principle in the contraction of transcendental notions: they are not contracted by something added in which they themselves are not included, but contract through themselves alone, by a new mode of explication and not by a new mode of addition, as St. Thomas teaches in question 1 of On Truth, art. 1.¹¹ Hence even the two highest genera differ by their whole selves and not through something added, as we explained more fully above when treating the analogy of being. There we showed that being is abstracted not by excluding inferiors, nor is it contracted by addition, but by a more or less explicit expression of the same thing. Because of this difference in mode and expression, it is not redundant or repetitive to say “a being in itself,” since in itself explains a mode different from that expressed by real being.

To the second, one says that what is constituted from an accident and a substance is not a being in itself, but a being per accidens. Moreover, it consists of two things, one of which—whiteness—is inhering and therefore is not, in every part of itself, absolved from inhering, which is required for it to be absolutely a being in itself and not in another. As to the other part concerning an accident separated from its subject, one says that it is not in itself intrinsically, as the notion of substance requires, but by the extrinsic conservation of God, who continues the accident’s being without the support of substance. Hence that accident expresses an aptitude for inhering, which substance does not express.

To the third, one says that underlying constitutes substance as substance most of all, not with respect to its nature, which does not admit of more or less, but with respect to the exercise of supporting and the office of being under other things, which presupposes a subsistent and consequently constituted nature.