by Aristotle
Nothing that is has a nature,
But only mixing and parting of the mixed,
And nature is but a name applied to them by men.2
Hence as regards the things that are or come to be by nature, though that from which they naturally come to be or are is already present, we say they have not their [5] nature yet, unless they have their form or shape. That which comprises both of these exists by nature, e.g. the animals and their parts; and nature is both the first matter (and this in two senses, either first, counting from the thing, or first in general, e.g. in the case of works in bronze, bronze is first with reference to them, but in general [10] perhaps water is first, if all things that can be melted are water), and the form or substance, which is the end of the process of becoming. And from this sense of ‘nature’ every substance in general is in fact, by an extension of meaning, called a ‘nature’, because the nature of a thing is one kind of substance.
From what has been said, then, it is plain that nature in the primary and strict sense is the substance of things which have in themselves, as such, a source of movement; for the matter is called the nature because it is qualified to receive this, [15] and processes of becoming and growing are called nature because they are movements proceeding from this. And nature in this sense is the source of the movement of natural objects, being present in them somehow, either potentially or actually.
5 · We call the necessary (1) that without which, as a condition, a thing [20] cannot live, e.g. breathing and food are necessary for an animal; for it is incapable of existing without these.—(2) The conditions without which good cannot be or come to be, or without which we cannot get rid or be freed of evil, e.g. drinking the medicine is necessary in order that we may be cured of disease, and sailing to Aegina is necessary in order that we may get our money.—(3) The compulsory and [25] compulsion, i.e. that which impedes and hinders contrary to impulse and choice. For the compulsory is called necessary; that is why the necessary is painful, as Evenus says: ‘For every necessary thing is ever irksome’. And compulsion is a form of [30] necessity, as Sophocles says: ‘Force makes this action a necessity’.3 And necessity is held to be something that cannot be persuaded—and rightly, for it is contrary to the movement which accords with choice and with reasoning.—(4) We say that that which cannot be otherwise is necessarily so. And from this sense of necessary all the [35] others are somehow derived; for as regards the compulsory we say that it is necessary to act or to be acted on, only when we cannot act according to impulse [1015b1] because of the compelling force,—which implies that necessity is that because of which the thing cannot be otherwise; and similarly as regards the conditions of life and of good, when in the one case good, in the other life and being, are not possible [5] without certain conditions, these are necessary, and this cause is a kind of necessity.—Again, (5) demonstration is a necessary thing, because the conclusion cannot be otherwise, if there has been demonstration in the full sense; and the causes of this necessity are the first premises, i.e. the fact that the propositions from which the deduction proceeds cannot be otherwise.
Now some things owe their necessity to something other than themselves; [10] others do not, while they are the source of necessity in other things. Therefore the necessary in the primary and strict sense is the simple; for this does not admit of more states than one, so that it does not admit even of one state and another; for it would thereby admit of more than one. If, then, there are certain eternal and unmovable things, nothing compulsory or against their nature attaches to them. [15]
6 · We call one (1) that which is one by accident, (2) that which is one by its own nature. (1) Instances of the accidentally one are Coriscus and musical, and musical Coriscus (for it is the same thing to say ‘Coriscus’ and ‘musical’, and ‘musical Coriscus’), and musical and just, and musical Coriscus and just Coriscus. [20] For all these are called one by accident, just and musical because they are accidents of one substance, musical and Coriscus because the one is an accident of the other; and similarly in a sense musical Coriscus is one with Coriscus, because one of the [25] parts in the formula is an accident of the other, i.e. musical is an accident of Coriscus; and musical Coriscus is one with just Coriscus, because both have parts which are accidents of one and the same subject. The case is similar if the accident is predicated of a class or of any universal term, e.g. if one says that man is the same [30] as musical man; for this is either because musical is an accident of man, which is one substance, or because both are accidents of some individual, e.g. Coriscus. Both, however, do not belong to him in the same way, but one doubtless as genus and in the substance, the other as a state or affection of the substance.
[35] The things, then, that are called one by accident, are called so in this way. (2) Of things that are called one in virtue of their own nature some (a) are so called [1016a1] because they are continuous, e.g. a bundle is made one by a band, and pieces of wood are made one by glue; and a line, even if it is bent, is called one if it is continuous, as each part of the body is, e.g. the leg or the arm. Of these themselves, the continuous by nature are more one than the continuous by art. A thing is called [5] continuous which has by its own nature one movement and cannot have any other; and the movement is one when it is indivisible, and indivisible in time. Those things are continuous by their own nature which are one not merely by contact; for if you put pieces of wood touching one another, you will not say these are one piece of wood or one body or one continuum of any other sort. Things, then, that are [10] continuous in any way are called one, even if they admit of being bent, and still more those which cannot be bent, e.g. the shin or the thigh is more one than the leg, because the movement of the leg need not be one. And the straight line is more one than the bent; but that which is bent and has an angle we call both one and not one [15] because its movement may be either simultaneous or not simultaneous; but that of the straight line is always simultaneous, and no part of it which has magnitude rests while another moves, as in the bent line.
(b) Things are called one in another sense because the substratum does not differ in kind; it does not differ in the case of things whose kind is indivisible to the [20] sense. The substratum meant is either the nearest to, or the furthest from, the final state. For, on the one hand, wine is said to be one and water is said to be one, qua indivisible in kind; and, on the other hand, all juices, e.g. oil and wine, are said to be one, and so are all things that can be melted, because the ultimate substratum of all is the same; for all of these are water or air.
(c) Those things are called one whose genus is one though distinguished by [25] opposite differentiae; and these are all called one because the genus which underlies the differentiae is one (e.g. horse, man, and dog are one, because all are animals), and in a way similar to that in which the matter is one. These are sometimes called one in this way, but sometimes it is the higher genus that is said to be the same (if [30] they are infimae species of their genus)—the genus above the proximate genera, e.g. the isosceles and the equilateral are one and the same figure because both are triangles, but they are not the same triangles.
(d) Two things are called one, when the formula which states the essence of one is indivisible from another formula which shows the essence of the other (though in itself every formula is divisible). Thus even that which has increased or [35] is diminishing is one, because its formula is one, as, in the case of planes, is the formula of their form. In general those things, the thought of whose essence is [1016b1] indivisible and cannot separate them either in time or in place or in formula, are most of all one, and of these especially those which are substances. For in general those things that do not admit of division are one in so far as they do not admit of it, e.g. if something qua man does not admit of division, it is one man; if qua animal, it [5] is one animal; if qua magnitude, it is one magnitude.—Now most things are called one because they do or have or suffer or are related to something else that is one, but the things that are primarily calle
d one are those whose substance is one,—and one either in continuity or in form or in formula; for we count as more than one either things that are not continuous, or those whose form is not one, or those whose [10] formula is not one.
(e) While in a sense we call anything one if it is a quantity and continuous, in a sense we do not unless it is a whole, i.e. unless it has one form; e.g. if we saw the parts of a shoe put together anyhow we should not call them one all the same (unless because of their continuity); we do this only if they are put together so as to be a [15] shoe and have thereby some one form. This is why the circle is of all lines most truly one, because it is whole and complete.
What it is to be one is to be a beginning of number; for the first measure is the beginning, for that by which we first know each class is the first measure of the class; the one, then, is the beginning of the knowable regarding each class. But the [20] one is not the same in all classes. For here it is a quartertone, and there it is the vowel or the consonant; and there is another unit of weight and another of movement. But everywhere the one is indivisible either in quantity or in kind. That which is indivisible in quantity and qua quantity is called a unit if it is not divisible [25] in any dimension and is without position, a point if it is not divisible in any dimension and has position, a line if it is divisible in one dimension, a plane if in two, a body if divisible in quantity in all—i.e. in three—dimensions. And, reversing the order, that which is divisible in two dimensions is a plane, that which is divisible in one a line, that which is in no way divisible in quantity is a point or a unit—that which has not position a unit, that which has position a point. [30]
Again, some things are one in number, others in species, others in genus, others by analogy; in number those whose matter is one, in species those whose formula is one, in genus those to which the same figure of predication applies, by analogy those which are related as a third thing is to a fourth. The latter kinds of unity are always [35] found when the former are, e.g. things that are one in number are one in species, while things that are one in species are not all one in number; but things that are one in species are all one in genus, while things that are so in genus are not all one in [1017a1] species but are all one by analogy; while things that are one by analogy are not all one in genus.
Evidently ‘many’ will have uses corresponding to those of ‘one’; some things are many because they are not continuous, others because their matter—either the [5] proximate matter or the ultimate—is divisible in kind, others because the formulae which state their essence are more than one.
7 · Things are said to be (1) in an accidental sense, (2) by their own nature.
(1) In an accidental sense, e.g., we say the just is musical, and the man is [10] musical and the musical is a man, just as we say the musical builds, because the builder happens to be musical or the musical happens to be a builder; for here ‘one thing is another’ means ‘one is an accident of another’. So in the cases we have mentioned; for when we say the man is musical and the musical is a man, or the [15] white is musical or the musical is white, the last two mean that both attributes are accidents of the same thing; the first that the attribute is an accident of that which is; while the musical is a man means that musical is an accident of man. In this sense, too, the not-white is said to be, because that of which it is an accident is. Thus [20] when one thing is said in an accidental sense to be another, this is either because both belong to the same thing, and this is, or because that to which the attribute belongs is, or because the subject which has as an attribute that of which it is itself predicated, itself is.
(2) Those things are said in their own right to be that are indicated by the figures of predication; for the senses of ‘being’ are just as many as these figures. [25] Since some predicates indicate what the subject is, others its quality, others quantity, others relation, others activity or passivity, others its place, others its time, ‘being’ has a meaning answering to each of these. For there is no difference between ‘the man is recovering’ and ‘the man recovers’, nor between ‘the man is walking’ or [30] ‘cutting’ and ‘the man walks’ or ‘cuts’; and similarly in all other cases.
(3) ‘Being’ and ‘is’ mean that a statement is true, ‘not being’ that it is not true but false,—and this alike in affirmation and negation; e.g. ‘Socrates is musical’ means that this is true, or ‘Socrates is not-white’ means that this is true; but ‘the diagonal of the square is not commensurate with the side’ means that it is false to say it is.
(4) Again, ‘being’ and ‘that which is’, in these cases we have mentioned, sometimes [1017b1] mean being potentially, and sometimes being actually. For we say both of that which sees potentially and of that which sees actually, that it is seeing, and both of that which can use knowledge and of that which is using it, that it knows, and both [5] of that to which rest is already present and of that which can rest, that it rests. And similarly in the case of substances we say the Hermes is in the stone, and the half of the line is in the line, and we say of that which is not yet ripe that it is corn. When a thing is potential and when it is not yet potential must be explained elsewhere.
[10] 8 · We call substances (1) the simple bodies, i.e. earth and fire and water and everything of the sort, and in general bodies and the things composed of them, both animals and divine beings, and the parts of these. All these are called substance because they are not predicated of a subject but everything else is [15] predicated of them.—(2) That which, being present in such things as are not predicated of a subject, is the cause of their being, as the soul is of the being of animals.—(3) The parts which are present in such things, limiting them and marking them as individuals, and by whose destruction the whole is destroyed, as the body is by the destruction of the plane, as some say, and the plane by the destruction of the line; and in general number is thought by some to be of this [20] nature; for if it is destroyed, they say, nothing exists, and it limits all things.—(4) The essence, the formula of which is a definition, is also called the substance of each thing.
It follows, then, that substance has two senses, (a) the ultimate substratum, which is no longer predicated of anything else, and (b) that which is a ‘this’ and separable—and of this nature is the shape or form of each thing. [25]
9 · We call the same (1) that which is the same in an accidental sense, e.g. white and musical are the same because they are accidents of the same thing, and man and musical because the one is an accident of the other; and the musical is man because it is an accident of man. And the complex notion is the same as either of the [30] simple ones and each of these is the same as it; for man and musical are said to be the same as musical man, and this is the same as they. This is why all of these statements are made not universally; for it is not true to say that every man is the same as musical; for universal attributes belong to things in virtue of their own nature, but accidents do not belong to them in virtue of their own nature, but are [1018a1] predicated without qualification only of the individuals. For Socrates and musical Socrates are thought to be the same; but ‘Socrates’ is not predicable of more than one subject, and therefore we do not say ‘every Socrates’ as we say ‘every man’.
Some things are said to be the same in this sense; (2) things are said to be the [5] same by their own nature in as many ways as they are said to be one; for both the things whose matter is one either in kind or in number, and those whose substance is one, are said to be the same. Clearly, therefore, sameness is a unity of the being either of more than one thing or of one thing when it is treated as more than one, i.e. when we say a thing is the same as itself; for we treat it as two.
Things are called other if either their kinds or their matters or the formulae of [10] their substance are more than one; and in general ‘other’ has uses corresponding to those of ‘the same’.
We call different (1) those things which though other are the same in some respect, only not in number but either in species or in genus or by ana
logy; (2) those whose genus is other, and contraries, and all things that have their otherness in their substance.
Those things are called like which have the same attributes in every respect, [15] and those which have more attributes the same than different, and those whose quality is one; and that which shares with another thing the greater number or the more important of the attributes (each of them one of two contraries) in respect of which things are capable of altering, is like that other thing. The uses of ‘unlike’ correspond to those of ‘like’.
10 · We call opposites contradictories, and contraries, and relative terms, [20] and privation and possession, and the extremes from which and into which generation and dissolution take place; and the attributes that cannot be present at the same time in that which is receptive of both, are said to be opposed,—either themselves or their constituents. Grey and white do not belong at the same time to the same thing; therefore their constituents are opposed.
[25] We call contraries (1) those attributes that differ in genus, which cannot belong at the same time to the same subject, (2) the most different of the things in the same genus, (3) the most different of the attributes in the same receptive material, (4) the most different of the things that fall under the same capacity, (5) [30] the things whose difference is greatest either absolutely or in genus or in species. The other things that are called contrary are so called, some because they possess contraries of the above kind, some because they are receptive of such, some because they are productive of or susceptible to such, or are producing or suffering them, or [35] are losses or acquisitions, or possessions or privations, of such. Since ’One’ and ‘being’ have many senses, the other terms which are used with reference to these, and therefore ‘same’, ‘other’, and ‘contrary’, must correspond, so that they must be ‘other’ for each category.