Lecture 1 — Kinds of matter in sensible substances

It is necessary, then, to argue from the points which have been made, and after making a summary, to bring our investigations to a close.

It has been stated that it is the causes, principles, and elements of substances which are being sought (1042a4).

Now some substances are admitted by all, but there are others about which some thinkers have expressed views peculiar to themselves. Those which are admitted by all are physical substances, such as fire, earth, water, and the other simple bodies; plants and their parts; animals and the parts of animals; and finally the heaven and its parts. But certain other thinkers make the peculiar claim that the forms and the objects of mathematics are substances (1028b16).

From other arguments, it also follows that there are other substances, namely, the essence and the underlying subject. Again, from another point of view, a genus is substance to a greater degree than species, and a universal to a greater degree than singular things (1028b33). And the ideas have a connection with the universal and the genus, for they seem to be substances on the same grounds.

Further, since the essence is substance, and the definition is the intelligible expression of the essence, we have examined both the definition and everything that is predicated essentially (1029b1–1032a6).

And since the definition of a thing is its account, and the account has parts, then, concerning the notion of part, it was also necessary to consider what things are parts of substance and what are not, and whether these are necessary to the definition (1035b3–1038a30).

Further, neither the universal nor the genus is substance (1038b1–1040b27). Related questions concerning the ideas and the objects of mathematics must be examined later on, for some say that these are substances in addition to sensible ones. But now we must treat those things that all admit to be substances, and these are sensible substances.

All sensible substances have matter. And the underlying subject is substance; although, in another sense, the matter is such (by “matter” I mean that which is not a particular thing actually, but potentially).

In another sense, [the substance] is the intelligible structure or form, which is a particular thing and is separable in thought.

In a third sense, [the substance] is the thing composed of these, which alone is subject to generation and corruption, and is separable in an absolute sense.

For, according to the intelligible structure of substances, some are separable and others are not.

Now, it is evident that matter is substance, for in every process of change between contraries, there is something which underlies these changes. For example, in change of place, there is something which is now here and afterward somewhere else.

In change of size, that which is now of such a size and afterward smaller or greater. In change of quality, that which is now healthy and afterward diseased.

And similarly, in change of substance, there is something which is now in the process of generation and afterward in the process of corruption, and which is now a subject and this particular thing and afterward a subject of privation.

And the other changes follow upon this change, but this change does not follow upon one or two of the others. For if a thing has matter which is subject to change of place, it is not necessary that it also have matter which is generable and corruptible. The difference between coming-to-be in an absolute sense and coming-to-be in a qualified sense has been explained in the Physics.

1681. Having dealt with substance by means of the logical method in book 7 (that is, by examining the definition and its parts and other things of this kind which are considered from the viewpoint of argument), the Philosopher now intends in book 8 to deal with sensible substances through their proper principles, by applying to those substances the things that were investigated above by means of the logical method. This is divided into two parts.

In the first (1042a3; [1681]), he links up this discussion with the preceding one;

in the second (1042a25; [1686]), he carries out his intention, at all sensible substances.

In regard to the first, he does three things.

First, he states in a general way what he intends to do.

Second (1042a4; [1682]), he repeats some of the statements which have been made, at it has been stated.

Third (1042a17; [1685]), he links up the foregoing discussion with the one that is to come, at further, since the essence.

Thus, he first says (1042a3) that, since many of the statements made about substance in book 7 belong to the consideration of logic, we must reason from the statements which have been made so that the things stated from the viewpoint of logic may be applied to things existing in reality. And after making a summary, that is, after bringing these together again in a brief and summary way, we must bring our investigation to a close by completing the treatise on substance. He does this by discussing those things that were omitted from the foregoing treatise.

1682. It has been stated (1042a4). Here he repeats some of the statements which have been made, because it was stated in book 7 (1028b2; [1260]) that the principal objects of our search in this science are the causes, principles, and elements of substances. For since this science investigates as its proper subject being in general, and this is divided into substance and the nine genera of accidents, and a knowledge of accidents depends upon substance—as was shown in book 7 (1030b14–1030b28; [1342–50])—it follows that this science is principally concerned with substances. And since we know each thing only when we know its principles and causes, it also follows that this science must be principally concerned with the principles, causes, and elements of substances. The way in which these three differ has been shown above in book 5 (1012b34–1014b3; [751–807]).

1683. Now some substances (1042a6). Then he repeats one of the points discussed above, namely, the various senses in which “substance” is used.

First, he gives the things that are said to be substances existing among natural things. Among these there are some whose existence is admitted by all thinkers, namely, sensible substances such as earth, water, and the other elements; above these, in the order of their nobility and perfection, plants and animals and their parts; lastly, the heaven and its parts, like the orbs and the stars, which surpass in nobility the other sensible substances.

However, there are some substances whose existence is not admitted by all, but only by certain particular thinkers who claim that the forms and the objects of mathematics have separate existence. They adopted this position because they thought that, for every abstraction of the intellect, there is a corresponding abstraction in reality. Thus, because the intellect considers the universal apart from particular things, as “man” apart from Socrates and Plato, they held that the forms have separate existence of themselves. And, since the intellect considers some forms apart from sensible material things, like curvature (whose concept does not contain nose, as does the concept of snub-nose) and a line and other things of this kind, which we call the objects of mathematics, they also held that the objects of mathematics have separate existence.

1684. From other arguments (1042a12). Here he gives the different ways in which substance is considered from the viewpoint of its intelligible structure. There are two of these.

The first is that substance means the quiddity of any natural substance, and this is merely the whatness of a natural being.

In the second way, substance is considered in a different sense, that is, in the sense that a genus is said to be substance to a greater degree than species, and a universal to a greater degree than singular things, as some men held according to what was treated in the questions in book 3 (998a21–999a16; [423–42]).

And connected with this way of considering substance, according to which both a genus and a universal are called substances, is the theory of ideas—or forms, as Aristotle called them above (1042a6; [1683]). For this theory maintains that both ideas and universals are substances on the same grounds.

1685. Further, since the essence (1042a17). He links up this discussion with the preceding one by stating what has been solved and what remains to be solved. He says that, since the essence is substance, and the intelligible expression which signifies it is the definition, for this reason, it was necessary for this reason to deal with definition in the preceding book. And since a definition is composed of those attributes which are predicated of a thing per se, it was also necessary in that book to settle the issue of essential predication (1029b1–1032a6; [1299–380]).

Further, since the definition of a thing is its intelligible expression and this is made up of parts, it was also necessary to determine what parts are parts of the thing defined and what are not; and whether the parts of the definition and those of the thing defined are the same (1035b3–1038a30; [1482–565]). Another text has whether the parts of the definition must be defined, but the first version is better. In book 7 (1038b1–1040b27; [1566–647]), it was shown also that neither the universal nor the genus is substance. Thus, the entire study which may be made of definitions and substance was carried out in book 7. But of those substances which exist in reality, it will be necessary to examine later the ideas and the objects of mathematics, which one school of thinkers claim to subsist by themselves apart from sensible substances. That examination is done in the last books of this work.

But now it is necessary to treat at once of those substances which all men admit to exist, namely, sensible substances, so that we may proceed from what has been made evident to what as yet remains unknown.

Sensible substance is matter, form, & composite

1686. All sensible substances (1042a25). Having linked up the foregoing discussion with the one that is to come, the Philosopher begins here to treat of sensible substances by investigating their principles. This is divided into two parts.

In the first [1686], he establishes what is true concerning matter and form, which are the principles of sensible substances.

In the second (1045a7; [1755]), he considers the way in which they are united to each other, at it seems that we must.

In regard to the first, he does two things.

First, he shows that matter and form are principles of sensible substances.

Second (1043a29; [1705]), he deals with those points which must be investigated about each of these principles, at and we must not.

In regard to the first, he does two things.

First, he shows that matter is a principle of sensible substances;

and second (1042b9; [1691]), that the same is true of form, at but since that which has the character of a subject.

In regard to the first, he does three things.

First, he shows what matter is by distinguishing it from the other ways in which substance is considered. Hence he says that all sensible substances have matter; the reason is that all are in motion, and motion does not exist without matter.

1687. But it must be noted that in one sense “substance” means matter, and in another, form, and in still another, the thing composed of these. For “matter” is called substance not as though it were a being considered to have actual existence in itself, but as something capable of being actual (and this is said to be a particular thing). And “form,” which is also termed the intelligible structure because the intelligible structure of the species is derived from it, is called substance inasmuch as it is something actual, and inasmuch as it is separable from matter in thought, but not in reality. And the thing composed of these is called substance inasmuch as it is something separable in an absolute sense, that is, capable of existing separately by itself in reality. It alone is subject to generation and corruption. For neither form nor matter are generated or corrupted, except accidentally.

And although the composite is separable in an absolute sense, yet some of the other things that are called substances are separable in thought and some are not. For a form is separable in thought because it can be understood without understanding individuating sensible matter, but matter cannot be understood without understanding form, since it is apprehended only inasmuch as it is in potency to form.

Or the statements can mean that, according to the intelligible structure of substances, that is, of forms, some are separable in their intelligible structure, as the objects of mathematics, and others are not, as natural forms.

Or again, it may mean that there are certain separate forms existing without matter, about which he will establish the truth later on [2447–54].

1688. Now, it is evident (1042a32). Second, he says that, in sensible substances, we must posit matter as substance and subject. For in every change between contraries, there must be a subject common to the termini of the change. For example, in change of place there is a common subject which is now here and afterward somewhere else, and in growth, there is a common subject which now has so much quantity and afterward is smaller (if the change is decrease) or greater (if it is increase). And in alteration, there is a common subject which is now healthy and afterward diseased. Hence, since there is substantial change—that is, generation and corruption—there must be a common subject which underlies the opposite changes of generation and corruption. And this is the subject for the termini that have been given, namely, form and privation, such that sometimes this subject is actual by reason of a form and sometimes it is the subject of the privation of that form.

1689. Now, from this argument of Aristotle, it is clear that substantial generation and corruption are the source from which we derive our knowledge of prime matter. For if prime matter had a form of its own by nature, it would be an actual thing by reason of that form. Hence, when an additional form would be given, such matter would not exist in an absolute sense by reason of that form, but would become this or that being; then there would be generation in a qualified sense but not in an absolute sense. Hence, all those who held that this first subject is a body, such as air or water, claimed that generation is the same as alteration. But it is clear from this argument what we must hold prime matter to be, for it is related to all forms and privations as the subject of qualitative change is to contrary qualities.

1690. And the other changes (1042b3). Here he shows that matter is not present in the same way in all sensible substances. He says that the other changes follow upon matter which is subject to generation and corruption, for if matter is subject to generation and corruption, it follows that it is subject to alteration and change of place. But this matter—that is, one which is subject to generation and corruption—does not follow upon all the other changes, especially change of place. For if a thing has matter which is subject to change of place, that is, by which it is potentially in a place, it does not follow that it also have matter which is generable and corruptible, namely, one which is subject to generation and corruption. For this kind of matter is lacking in the celestial bodies, in which there is a kind of alteration inasmuch as they are illuminated and deprived of light, but neither generation nor corruption.

Hence, he said one because of change of place, or two because of the kind of alteration just mentioned, although this is really not alteration, because illumination is not motion, but the terminus of motion. Thus, we must posit matter for every change according as there is in everything that changes a coming-to-be either in an absolute sense or in a qualified one. The difference between coming-to-be in an absolute sense and in a qualified one has been explained in Physics 1. For coming-to-be in an absolute sense belongs to substance, and coming-to-be in a qualified sense belongs to accidents.