LESSON 2

Three Classes of Substances

  Chapters 1 & 2: 1069a 30-1069b 32

             1028. Now there are three classes of substances. One is sensible, and of this class one kind is eternal and another perishable. The latter, such as plants and animals, all men recognize. But it is the eternal whose elements we must grasp, whether they are one or many. Another class is the immovable, which certain thinkers claim to have separate existence, some dividing it into two kinds, others maintaining that the separate Forms and the objects of mathematics are of one nature, and still others holding that only the objects of mathematics belong to this class. The first two classes of substance belong to the philosophy of nature since they involve motion; but the last belongs to a different science if there is no principle common to these three.

Chapter 2

             1029. Sensible substance is capable of being changed. And if change proceeds from opposites or from intermediates, yet not from all opposites (for the spoken word is not white) but only from a contrary, then there must be some underlying subject which can be changed from one contrary to another; for contraries themselves are not changed (730). Further, this subject remains, whereas a contrary does not remain. Therefore there is some third thing besides the contraries, and this is matter.

             1030. If, then, there are four kinds of change: either in substance or in quality or in quantity or in place, and if change in substance is generation and destruction without qualification, and change in quantity is increase and decrease, and change in attribute is alteration, and change in place is local motion, then the changes occurring in each case must be changes to contrary states. Therefore it must be the matter which is capable of being changed to both states.

             1031. And since being is twofold, every change is from potential being to actual being, for example, from potentially white to actually white. The same is true of increase and decrease. Hence not only can a thing come to be accidentally from nonbeing, but all things come to be from being, i.e., from potential being, not from actual being.

             1032. And this is the "One" of Anaxagoras; for it is better to maintain this view than to claim that "all things were together." And this is the "mixture" of Empedocles and Anaximander, and it recalls the statement of Democritus that all things were together potentially but not at all actually. Hence all these thinkers were touching upon matter.

             1033. Now all things which undergo change have matter, but different things have different matters; and of eternal things, those which are incapable of being generated but can be moved by local motion have matter. Yet they do not have that kind of matter which is subject to generation, but only such as is subject to motion from one place to another (697).

             1034. And one might raise the question from what kind of non-being generation could come about; for non-being is spoken of in three senses. If, then, one kind of non-being is potentiality, still it is not from anything at all that a thing comes to be, but different things come from different things. Nor is it enough to say that "all things were together," since they differ in their matter, for otherwise why would an infinite number of things be generated and not just one thing? For mind is one, so that if matter were also one, only that could come to be actually whose matter was in potentiality.

COMMENTARY

             2424. Having explained that philosophy is concerned chiefly with substances, here the Philosopher begins to deal with substances. This is divided into two parts. In the first (1028:C 2424) he makes a division of substance; and in the second (1029:C 2428) he treats the parts of this division ("Sensible substance").

             He accordingly says, first (1028), that there are three classes of substances. One is sensible, and this is divided into two kinds; for some sensible substances are eternal (the celestial bodies) and others perishable. Sensible and perishable substances, such as animals and plants, are recognized by all.

             2425. But it is "the other class of sensible substance," i.e., the eternal, whose principles we aim to discover in this book, whether their principles are one or many. He will investigate this by considering the separate substances, which are both the sources of motion and the ends of the celestial bodies, as will be made clear below (1086:C 2590-92). He uses elements in the broad sense here in place of principles; for strictly an element is only an intrinsic cause.

             2426. The third class of substance is the immovable and imperceptible. This class is not evident to all, but some men claim that it is separate from sensible things. The opinions of these men differ; for some divide separate substances into two kinds--the separate Forms, which they call Ideas, and the objects of mathematics. For just as a twofold method of separating is found in reason, one by which the objects of mathematics are separated from sensible matter, and another by which universals are separated from particular things, in a similar way they maintained that both universals, which they called separate Forms, and also the objects of mathematics, are separate in reality. But others reduced these two classes--the separate Forms and the objects of mathematics--to one nature. Both of these groups were Platonists. But another group, the Pythagoreans, did not posit separate Forms, but only the objects of mathematics.

             2427. Among these three classes of substances there is this difference, namely, that sensible substances, whether they are perishable or eternal, belong to the consideration of the philosophy of nature, which establishes the nature of movable being; for sensible substances of this kind are in motion. But separable and immovable substances belong to the study of a different science and not to the same science if there is no principle common to both kinds of substance; for if there were a common principle, the study of both kinds of substance would belong to the science which considers that common principle. The philosophy of nature, then, considers sensible substances only inasmuch as they are actual and in motion. Hence this science (first philosophy) considers both sensible substances and immovable substances inasmuch as both are beings and substances.

             2428. Sensible substance (1029).

             Then he establishes the truth about the above-mentioned substances. He does this, first (1029:C 2428), with regard to sensible substances; and second (1055:C 2488), with regard to immovable substances ("And since there are three").

             The first is divided into two parts. First, he investigates the principles of sensible substances; and second (1042:C 2455), he inquires whether the principles of substances and those of the other categories are the same ("In one sense").

             In regard to the first he does two things. First, he investigates the nature of matter; and second (1035:C 2441), the nature of form ("The causes or principles").

             In regard to the first he does two things. First, he states his views about matter. Second (1034:C 2437), he meets a difficulty ("And one might raise the question").

             In regard to the first he does two things. First, he shows that there is matter in sensible substances; and he also shows what kind of being matter is. Second (1033:C 2436), he shows how matter differs in different kinds of sensible substances ("Now all things").

             In regard to the first he does two things. First, he proceeds as described. Second (1031:C 2432), he meets an argument by which some of the ancient philosophers denied generation ("And since being is twofold").

             In regard to the first he does two things. First, he shows that there is matter in sensible substances. Second (1030:C 2431), he shows what kind of being matter is ("If, then, there are").

             He accordingly says, first (1029), that sensible substance is changeable, as has been pointed out, and every change is either from opposites or from intermediates, as has been shown above (384:C 723-24). Yet change does not proceed from any opposites whatever; for the white comes from the not-white, but not from just any not-white; for a word is not-white, yet a body does not become white from a word, but from a not-white which is black or some intermediate color. Hence he says that change proceeds from an opposite which is a contrary. And there can be no rejoinder based on change in substance on the ground that there is nothing contrary to substance. For in substance there is privation which is included in a sense among contraries, as has been shown in Book X (853:C 2050-53).

             2429. Hence, since every change is from one contrary to another, there must be some underlying subject which can be changed from one contrary to another. The Philosopher proves this in two ways. First, he argues on the ground that one contrary is not changed into another; for blackness itself does not become whiteness, so that, if there is a change from black to white, there must be something besides blackness which becomes white.

             2430. He proves the same point in another way, namely, from the fact that throughout every change something is found to remain. For example, in a change from black to white a body remains, whereas the other thing--the contrary black--does not remain. Therefore it is evident that matter is some third entity besides the contraries.

             2431. If, then, there are (1030).

             He now shows what kind of being matter is. He says that there are four kinds of change: simple generation and destruction, which is change in substance; increase and decrease, which is change in quantity; alteration, which is change in affections (and constitutes the third species of quality); and "local motion," or change of place, which pertains to the where of a thing. Now it has been shown that all of these changes involve the contrarieties that belong to each of these classes; for example, alteration involves contrariety of quality, increase involves contrariety of quantity, and so on for the others. And since in every change there is besides the contraries some third entity which is called matter, the thing undergoing the change, i.e., the subject of the change, considered just in itself, must be in potentiality to both contraries, otherwise it would not be susceptible of both or admit of change from one to the other. Thus, just as a body which is changed from white to black, qua body, is in potentiality to each of the two contraries, in a similar way in the generation of substance the matter, as the subject of generation and destruction, is of itself in potentiality both to form and to privation, and has actually of itself neither form nor privation.

             2432. And since being (1031).

             Here the Philosopher establishes the truth about matter itself, and in regard to this he does two things. First, he meets a difficulty. Second (1032:C 2435), he shows how some of the ancient philosophers offered a solution similar to the one mentioned above ("And this is the 'One'").

             He meets the difficulty of the ancient philosophers who did away with generation because they did not think that anything could come from non-being, since nothing comes from nothing, or that anything could come from being, since a thing would then be before it came to be.

             2433. The Philosopher meets this difficulty by showing how a thing comes to be both from being and from non-being. He says that being is twofold--actual and potential. Hence everything which is changed is changed from a state of potential being to one of actual being; for example, a thing is changed from being potentially white to being actually white. The same thing holds true of the motion of increase and decrease, since something is changed from being potentially large or small to being actually large or small. In the category of substance, then, all things come to be both from being and from non-being. A thing comes to be accidentally from non-being inasmuch as it comes to be from a matter subject to privation, in reference to which it is called non-being. And a thing comes to be essentially from being--not actual being but potential being--i.e., from matter, which is potential being, as has been shown above (1030:C 2431).

             2434. Now it should be borne in mind that certain later thinkers wanted to oppose the above-mentioned principle of the ancient philosophers of nature (who denied generation and destruction and claimed that generation is merely alteration) when they said that generation comes about through detachment from some mixture or confused mass.

             2435. Hence, when the Philosopher in the third part of his division says "And this is the one (1032)," he shows that all who expressed this view wanted to adopt a position similar to the one mentioned above, but did not succeed in doing so. Therefore he says that this, namely, matter, which is in potentiality to all forms, is the "One" of which Anaxagoras spoke; for Anaxagoras said that everything which is generated from something else is present in that thing from which it comes to be. And so, not knowing how to distinguish between potentiality and actuality, he said that in the beginning all things were mixed together in one whole. But it is more fitting to posit a matter in which all things are present potentially than to posit one in which all things are present actually and simultaneously, as seems to be the case from what Anaxagoras said. This is what Empedocles also claimed, namely, that in the beginning all things were mixed or mingled together by friendship and later were separated out by strife. Anaximander similarly held that all contraries originally existed in one confused mass. And Democritus said that everything which comes to be first exists potentially and then actually. Hence it is evident that all these philosophers touched upon matter to some extent but did not fully comprehend it.

             2436. Now all things (1033).

             He shows that matter is not present in all sensible substances in the same way. He says that all things which undergo change must have matter, but of a different kind. For things which "are changed substantially," i.e., generated and destroyed, have a matter which is subject to generation and destruction, i.e., one which is in itself in potentiality both to forms and to privations. But the celestial bodies, which are eternal and not subject to generation, yet admit of change of place, have matter--not one which admits of generation and destruction or one which is in potentiality to form and to privation, but one which is in potentiality to the termini of local motion, i.e., the point from which motion begins and the point to which it tends.

             2437. And one might raise (1034).

             Then he meets a difficulty that pertains to the points established above. He says that, since generation is a change from non-being to being, one can ask from what sort of non-being generation proceeds; for non-being is said of three things. First, it is said of what does not exist in any way; and from this kind of non-being nothing is generated, because in reality nothing comes from nothing. Second, it is said of privation, which is considered in a subject; and while something is generated from this kind of non-being, the generation is accidental, i.e., inasmuch as something is generated from a subject to which some privation occurs. Third, it is said of matter itself, which, taken in itself, is not an actual being but a potential one. And from this kind of non-being something is generated essentially; or in his words, if one kind of non-being is potentiality, then from such a principle, i.e., non-being, something is generated essentially.

             2438. Yet even though something is generated from that kind of non-being which is being in potentiality, still a thing is not generated from every kind of non-being, but different things come from different matters. For everything capable of being generated has a definite matter from which it comes to be, because there must be a proportion between form and matter. For even though first matter is in potentiality to all forms, it nevertheless receives them in a certain order. For first of all it is in potency to the forms of the elements, and through the intermediary of these, insofar as they are mixed in different proportions, it is in potency to different forms. Hence not everything can come to be directly from everything else unless perhaps by being resolved into first matter.

             2439. This view is opposed to that of Anaxagoras, who claimed that anything at all comes to be from anything else. Nor is his assumption that all things were together in the beginning sufficient to support this view. For things differ by reason of matter inasmuch as there are different matters for different things. For if the matter of all things were one, as it is according to the opinion of Anaxagoras, why would an infinite number of things be generated and not just one thing? For Anaxagoras claimed that there is one agent, mind; and therefore, if matter too were one, only one thing would necessarily come to be, namely, that to which matter is in potentiality. For where there is one agent and one matter there must be one effect, as has been stated in Book X.

             2440. This argument holds good against Anaxagoras inasmuch as he claimed that mind needs matter in order to produce some effect. And if he claims that the first principle of things is mind, which produces matter itself, the first principle of the diversity of things will proceed from the order apprehended by the above-mentioned mind, which, inasmuch as it aims to produce different things, establishes different matters having an aptitude for a diversity of things.