Part 5

Substance, in the truest and primary and most definite sense of the word, is that which is neither predicable of a subject nor present in a subject; for instance, the individual man or horse. But in a secondary sense those things are called substances within which, as species, the primary substances are included; also those which, as genera, include the species. For instance, the individual man is included in the species 'man', and the genus to which the species belongs is 'animal'; these, therefore—that is to say, the species 'man' and the genus 'animal,-are termed secondary substances.

Substance, in the truest, primary, and most definite sense, is neither said of a subject nor present in a subject. An example is an individual man or horse. But in a secondary sense, the species that include primary substances are also called substances. So are the genera that include those species. For example, an individual man belongs to the species 'man', and that species belongs to the genus 'animal'. Therefore, the species 'man' and the genus 'animal' are called secondary substances.

It is plain from what has been said that both the name and the definition of the predicate must be predicable of the subject. For instance, 'man' is predicated of the individual man. Now in this case the name of the species 'man' is applied to the individual, for we use the term 'man' in describing the individual; and the definition of 'man' will also be predicated of the individual man, for the individual man is both man and animal. Thus, both the name and the definition of the species are predicable of the individual.

The discussion so far makes one point clear. Both the name and the definition of the predicate must apply to the subject. For example, 'man' is predicated of an individual man. In this case, the species name 'man' applies to the individual because we use 'man' to describe him. The definition of 'man' also applies to the individual man because he is both a man and an animal. So both the name and the definition of the species apply to the individual.

With regard, on the other hand, to those things which are present in a subject, it is generally the case that neither their name nor their definition is predicable of that in which they are present. Though, however, the definition is never predicable, there is nothing in certain cases to prevent the name being used. For instance, 'white' being present in a body is predicated of that in which it is present, for a body is called white: the definition, however, of the colour 'white' is never predicable of the body.

On the other hand, consider things present in a subject. Generally, neither their names nor their definitions can be applied to the subject in which they are present. Although their definitions can never be applied to that subject, their names can be used in some cases. For example, 'white' is present in a body and can be applied to that body, since a body is called white. But the definition of the colour 'white' can never be applied to the body.

Everything except primary substances is either predicable of a primary substance or present in a primary substance. This becomes evident by reference to particular instances which occur. 'Animal' is predicated of the species 'man', therefore of the individual man, for if there were no individual man of whom it could be predicated, it could not be predicated of the species 'man' at all. Again, colour is present in body, therefore in individual bodies, for if there were no individual body in which it was present, it could not be present in body at all. Thus everything except primary substances is either predicated of primary substances, or is present in them, and if these last did not exist, it would be impossible for anything else to exist.

Everything except primary substances either can be said of a primary substance or is present in a primary substance. Specific examples make this clear. 'Animal' is said of the species 'man', so 'animal' is also said of an individual man. For if 'animal' could not be said of any individual man, it could not be said of the species 'man'. Likewise, colour is present in body, so colour is present in individual bodies. For if colour were not present in any individual body, colour could not be present in body at all. Thus everything except primary substances either is said of primary substances or is present in them. If primary substances did not exist, nothing else could exist.

Of secondary substances, the species is more truly substance than the genus, being more nearly related to primary substance. For if any one should render an account of what a primary substance is, he would render a more instructive account, and one more proper to the subject, by stating the species than by stating the genus. Thus, he would give a more instructive account of an individual man by stating that he was man than by stating that he was animal, for the former description is peculiar to the individual in a greater degree, while the latter is too general. Again, the man who gives an account of the nature of an individual tree will give a more instructive account by mentioning the species 'tree' than by mentioning the genus 'plant'.

Among secondary substances, the species is more truly substance than the genus because it is closer to primary substance. For if someone explained what a primary substance is, naming its species would be more informative than naming its genus. Naming the species would also describe the subject more accurately. For example, describing an individual man as a man would be more informative than describing him as an animal. The first description is more specific to the individual, while the second is too general. Likewise, someone explaining the nature of an individual tree would give a more informative account by naming the species 'tree'. Naming the genus 'plant' would be less informative.

Moreover, primary substances are most properly called substances in virtue of the fact that they are the entities which underlie everything else, and that everything else is either predicated of them or present in them. Now the same relation which subsists between primary substance and everything else subsists also between the species and the genus: for the species is to the genus as subject is to predicate, since the genus is predicated of the species, whereas the species cannot be predicated of the genus. Thus we have a second ground for asserting that the species is more truly substance than the genus.

Moreover, primary substances are most properly called substances because they are the entities underlying everything else. Everything else is either predicated of primary substances or present in them. Now species and genus have the same relationship as primary substance and everything else. Species stands to genus as subject stands to predicate. This is because the genus is predicated of the species, but the species cannot be predicated of the genus. So we have a second reason for saying that species is more truly substance than genus.

Of species themselves, except in the case of such as are genera, no one is more truly substance than another. We should not give a more appropriate account of the individual man by stating the species to which he belonged, than we should of an individual horse by adopting the same method of definition. In the same way, of primary substances, no one is more truly substance than another; an individual man is not more truly substance than an individual ox.

Among species, except those that are also genera, none is more truly a substance than another. Naming the species gives no more appropriate an account of an individual man than of an individual horse. Likewise, among primary substances, none is more truly a substance than another. An individual man is not more truly a substance than an individual ox.

It is, then, with good reason that of all that remains, when we exclude primary substances, we concede to species and genera alone the name 'secondary substance', for these alone of all the predicates convey a knowledge of primary substance. For it is by stating the species or the genus that we appropriately define any individual man; and we shall make our definition more exact by stating the former than by stating the latter. All other things that we state, such as that he is white, that he runs, and so on, are irrelevant to the definition. Thus it is just that these alone, apart from primary substances, should be called substances.

Once we exclude primary substances, we rightly give the name 'secondary substance' only to species and genera. For species and genera alone, among all predicates, tell us what a primary substance is. We properly define any individual man by stating his species or genus. And stating his species makes our definition more exact than stating his genus. Everything else we say, such as that he is white or that he runs, is irrelevant to the definition. So, apart from primary substances, only species and genera rightly deserve to be called substances.

Further, primary substances are most properly so called, because they underlie and are the subjects of everything else. Now the same relation that subsists between primary substance and everything else subsists also between the species and the genus to which the primary substance belongs, on the one hand, and every attribute which is not included within these, on the other. For these are the subjects of all such. If we call an individual man 'skilled in grammar', the predicate is applicable also to the species and to the genus to which he belongs. This law holds good in all cases.

Further, primary substances most properly deserve the name because they underlie everything else and serve as its subjects. The species and genus to which a primary substance belongs have the same relationship to attributes outside those categories. For the species and genus serve as subjects of all such attributes. If we call an individual man 'skilled in grammar', that predicate also applies to his species and genus. This rule holds in all cases.

It is a common characteristic of all substance that it is never present in a subject. For primary substance is neither present in a subject nor predicated of a subject; while, with regard to secondary substances, it is clear from the following arguments (apart from others) that they are not present in a subject. For 'man' is predicated of the individual man, but is not present in any subject: for manhood is not present in the individual man. In the same way, 'animal' is also predicated of the individual man, but is not present in him. Again, when a thing is present in a subject, though the name may quite well be applied to that in which it is present, the definition cannot be applied. Yet of secondary substances, not only the name, but also the definition, applies to the subject: we should use both the definition of the species and that of the genus with reference to the individual man. Thus substance cannot be present in a subject.

All substance has one feature in common: it is never present in a subject. Primary substance is neither present in a subject nor predicated of a subject. For secondary substances, the following arguments, among others, show that they are not present in a subject. For 'man' is predicated of the individual man, but is not present in any subject. This is because manhood is not present in the individual man. In the same way, 'animal' is also predicated of the individual man, but is not present in him. Again, when something is present in a subject, its name may well apply to the subject, but its definition cannot. Yet for secondary substances, both the name and the definition apply to the subject. We would apply both the definition of the species and the definition of the genus to the individual man. Thus substance cannot be present in a subject.

Yet this is not peculiar to substance, for it is also the case that differentiae cannot be present in subjects. The characteristics 'terrestrial' and 'two-footed' are predicated of the species 'man', but not present in it. For they are not in man. Moreover, the definition of the differentia may be predicated of that of which the differentia itself is predicated. For instance, if the characteristic 'terrestrial' is predicated of the species 'man', the definition also of that characteristic may be used to form the predicate of the species 'man': for 'man' is terrestrial.

Yet substance is not unique in this respect, because differentiae also cannot be present in subjects. The characteristics 'terrestrial' and 'two-footed' are predicated of the species 'man', but are not present in that species. For these characteristics are not in man. Moreover, the definition of a differentia may be predicated of the same subject as the differentia itself. For example, if 'terrestrial' is predicated of the species 'man', its definition may also serve as a predicate of 'man'. For 'man' is terrestrial.

The fact that the parts of substances appear to be present in the whole, as in a subject, should not make us apprehensive lest we should have to admit that such parts are not substances: for in explaining the phrase 'being present in a subject', we stated' that we meant 'otherwise than as parts in a whole'.

The parts of substances seem to be present in the whole as in a subject. But we should not worry that we must therefore admit these parts are not substances. For when we explained 'being present in a subject', we specified 'otherwise than as parts in a whole'.

It is the mark of substances and of differentiae that, in all propositions of which they form the predicate, they are predicated univocally. For all such propositions have for their subject either the individual or the species. It is true that, inasmuch as primary substance is not predicable of anything, it can never form the predicate of any proposition. But of secondary substances, the species is predicated of the individual, the genus both of the species and of the individual. Similarly the differentiae are predicated of the species and of the individuals. Moreover, the definition of the species and that of the genus are applicable to the primary substance, and that of the genus to the species. For all that is predicated of the predicate will be predicated also of the subject. Similarly, the definition of the differentiae will be applicable to the species and to the individuals. But it was stated above that the word 'univocal' was applied to those things which had both name and definition in common. It is, therefore, established that in every proposition, of which either substance or a differentia forms the predicate, these are predicated univocally.

Substances and differentiae have a distinctive feature: whenever they serve as predicates, they are predicated univocally. For the subject of every such statement is either an individual or a species. Primary substance, however, cannot be predicated of anything, so it can never serve as a statement's predicate. But among secondary substances, the species is predicated of the individual. The genus is predicated of both the species and the individual. Similarly, differentiae are predicated of both species and individuals. Moreover, the definitions of the species and the genus apply to the primary substance. The definition of the genus also applies to the species. For everything predicated of a predicate is also predicated of the subject. Similarly, the definitions of the differentiae apply to both species and individuals. But as stated above, the word 'univocal' applies to things that share both a name and a definition. Therefore, whenever a substance or a differentia serves as a statement's predicate, it is predicated univocally.

All substance appears to signify that which is individual. In the case of primary substance this is indisputably true, for the thing is a unit. In the case of secondary substances, when we speak, for instance, of 'man' or 'animal', our form of speech gives the impression that we are here also indicating that which is individual, but the impression is not strictly true; for a secondary substance is not an individual, but a class with a certain qualification; for it is not one and single as a primary substance is; the words 'man', 'animal', are predicable of more than one subject.

All substance seems to refer to an individual thing. For primary substance, this is unquestionably true, because the thing is a single unit. With secondary substances, when we speak of 'man' or 'animal', our wording also suggests an individual thing. But this impression is not strictly accurate. A secondary substance is not an individual, but a class defined by certain qualities. For a secondary substance is not one single thing, as a primary substance is. The words 'man', 'animal', can apply to more than one subject.

Yet species and genus do not merely indicate quality, like the term 'white'; 'white' indicates quality and nothing further, but species and genus determine the quality with reference to a substance: they signify substance qualitatively differentiated. The determinate qualification covers a larger field in the case of the genus that in that of the species: he who uses the word 'animal' is herein using a word of wider extension than he who uses the word 'man'.

Yet species and genus do not merely indicate quality, as the term 'white' does. 'White' indicates quality and nothing more. But species and genus describe quality in relation to a substance. They identify a substance by its distinguishing qualities. The quality specified by a genus covers a wider range than the quality specified by a species. Someone using the word 'animal' uses a term with a broader scope than someone using the word 'man'.

Another mark of substance is that it has no contrary. What could be the contrary of any primary substance, such as the individual man or animal? It has none. Nor can the species or the genus have a contrary. Yet this characteristic is not peculiar to substance, but is true of many other things, such as quantity. There is nothing that forms the contrary of 'two cubits long' or of 'three cubits long', or of 'ten', or of any such term. A man may contend that 'much' is the contrary of 'little', or 'great' of 'small', but of definite quantitative terms no contrary exists.

Another feature of substance is that it has no opposite. What could be the opposite of a primary substance, such as an individual man or animal? There is none. Neither a species nor a genus has an opposite. But this feature is not unique to substance. Many other things, such as quantity, also have no opposite. There is no opposite of 'two cubits long', 'three cubits long', 'ten', or any similar term. Someone may argue that 'much' is the opposite of 'little', or 'great' of 'small'. But terms for definite quantities have no opposite.

Substance, again, does not appear to admit of variation of degree. I do not mean by this that one substance cannot be more or less truly substance than another, for it has already been stated that this is the case; but that no single substance admits of varying degrees within itself. For instance, one particular substance, 'man', cannot be more or less man either than himself at some other time or than some other man. One man cannot be more man than another, as that which is white may be more or less white than some other white object, or as that which is beautiful may be more or less beautiful than some other beautiful object. The same quality, moreover, is said to subsist in a thing in varying degrees at different times. A body, being white, is said to be whiter at one time than it was before, or, being warm, is said to be warmer or less warm than at some other time. But substance is not said to be more or less that which it is: a man is not more truly a man at one time than he was before, nor is anything, if it is substance, more or less what it is. Substance, then, does not admit of variation of degree.

Substance, again, does not seem to vary in degree. I do not mean that one substance cannot be more or less truly a substance than another. That has already been established. Rather, no individual substance varies in how fully it is what it is. For example, take a particular substance, 'man'. A man cannot be more or less a man than he is at another time or than another man. One man cannot be more of a man than another. By contrast, one white object may be more or less white than another white object. Likewise, one beautiful object may be more or less beautiful than another beautiful object. Moreover, the same quality is said to exist in something to different degrees at different times. A white body is said to be whiter at one time than before. Likewise, a warm body is said to be warmer or less warm than at another time. But a substance is not said to be more or less what it is. A man is not more truly a man at one time than before. Nor is anything, if it is a substance, more or less what it is. Substance, then, does not vary in degree.

The most distinctive mark of substance appears to be that, while remaining numerically one and the same, it is capable of admitting contrary qualities. From among things other than substance, we should find ourselves unable to bring forward any which possessed this mark. Thus, one and the same colour cannot be white and black. Nor can the same one action be good and bad: this law holds good with everything that is not substance. But one and the selfsame substance, while retaining its identity, is yet capable of admitting contrary qualities. The same individual person is at one time white, at another black, at one time warm, at another cold, at one time good, at another bad. This capacity is found nowhere else, though it might be maintained that a statement or opinion was an exception to the rule. The same statement, it is agreed, can be both true and false. For if the statement 'he is sitting' is true, yet, when the person in question has risen, the same statement will be false. The same applies to opinions. For if any one thinks truly that a person is sitting, yet, when that person has risen, this same opinion, if still held, will be false. Yet although this exception may be allowed, there is, nevertheless, a difference in the manner in which the thing takes place. It is by themselves changing that substances admit contrary qualities. It is thus that that which was hot becomes cold, for it has entered into a different state. Similarly that which was white becomes black, and that which was bad good, by a process of change; and in the same way in all other cases it is by changing that substances are capable of admitting contrary qualities. But statements and opinions themselves remain unaltered in all respects: it is by the alteration in the facts of the case that the contrary quality comes to be theirs. The statement 'he is sitting' remains unaltered, but it is at one time true, at another false, according to circumstances. What has been said of statements applies also to opinions. Thus, in respect of the manner in which the thing takes place, it is the peculiar mark of substance that it should be capable of admitting contrary qualities; for it is by itself changing that it does so.

The most distinctive feature of substance seems to be its ability to take on opposite qualities while remaining the same individual thing. We could find nothing other than substance with this feature. For example, one and the same colour cannot be both white and black. Nor can one and the same action be both good and bad. This rule holds for everything that is not substance. But one and the same substance can take on opposite qualities while keeping its identity. The same person is white at one time and black at another, warm at one time and cold at another. The same person is also good at one time and bad at another. Nothing else has this ability, though someone might argue that a statement or opinion is an exception. The same statement, as everyone agrees, can be both true and false. For if the statement 'he is sitting' is true, the same statement will be false when the person has stood up. The same applies to opinions. Suppose someone correctly believes that a person is sitting. When that person has stood up, the same opinion, if still held, will be false. Yet even if we allow this exception, there is still a difference in how these opposite qualities arise. Substances take on opposite qualities by changing themselves. Something hot becomes cold because it has changed its state. Likewise, something white becomes black, and something bad becomes good, through a process of change. In all other cases too, substances can take on opposite qualities by changing. But statements and opinions themselves remain unchanged in every respect. They take on opposite qualities because the facts change. The statement 'he is sitting' remains unchanged. But the statement is true at one time and false at another, depending on the circumstances. What has been said about statements also applies to opinions. Thus, the way substance takes on opposite qualities is distinctive. Substance takes on these qualities by itself changing.

If, then, a man should make this exception and contend that statements and opinions are capable of admitting contrary qualities, his contention is unsound. For statements and opinions are said to have this capacity, not because they themselves undergo modification, but because this modification occurs in the case of something else. The truth or falsity of a statement depends on facts, and not on any power on the part of the statement itself of admitting contrary qualities. In short, there is nothing which can alter the nature of statements and opinions. As, then, no change takes place in themselves, these cannot be said to be capable of admitting contrary qualities.

Suppose, then, someone objects that statements and opinions are an exception because they can take on opposite qualities. That argument is unsound. Statements and opinions are said to have this ability, not because they themselves change, but because something else changes. Whether a statement is true or false depends on the facts. It does not depend on any ability of the statement itself to take on opposite qualities. In short, nothing can change the nature of statements and opinions. Since statements and opinions do not themselves change, they cannot be said to take on opposite qualities.

But it is by reason of the modification which takes place within the substance itself that a substance is said to be capable of admitting contrary qualities; for a substance admits within itself either disease or health, whiteness or blackness. It is in this sense that it is said to be capable of admitting contrary qualities.

But a substance is said to be capable of having opposite qualities because of changes within the substance itself. For a substance can have either disease or health, whiteness or blackness, within itself. In this sense, a substance is said to be capable of having opposite qualities.

To sum up, it is a distinctive mark of substance, that, while remaining numerically one and the same, it is capable of admitting contrary qualities, the modification taking place through a change in the substance itself.

In short, substance has a distinctive feature. A substance can take on opposite qualities while remaining one and the same thing. These changes in qualities happen through a change in the substance itself.

Let these remarks suffice on the subject of substance.

These remarks are enough on the subject of substance.