Again, nature in the sense of a coming-to-be proceeds towards nature. For it is not like doctoring, which leads not to the art of doctoring but to health. Doctoring [15] must start from the art, not lead to it. But it is not in this way that nature is related to nature. What grows qua growing grows from something into something. Into what then does it grow? Not into that from which it arose but into that to which it tends. The shape then is nature.
Shape and nature are used in two ways. For the privation too is in a way form. [20] But whether in unqualified coming to be there is privation, i.e. a contrary, we must consider later.
2 · We have distinguished, then, the different ways in which the term ‘nature’ is used.
The next point to consider is how the mathematician differs from the student of nature; for natural bodies contain surfaces and volumes, lines and points, and these are the subject-matter of mathematics. [25]
Further, is astronomy different from natural science or a department of it? It seems absurd that the student of nature should be supposed to know the nature of sun or moon, but not to know any of their essential attributes, particularly as the writers on nature obviously do discuss their shape and whether the earth and the [30] world are spherical or not.
Now the mathematician, though he too treats of these things, nevertheless does not treat of them as the limits of a natural body; nor does he consider the attributes indicated as the attributes of such bodies. That is why he separates them; for in thought they are separable from motion, and it makes no difference, nor does any falsity result, if they are separated. The holders of the theory of Forms do the same, [35] though they are not aware of it; for they separate the objects of natural science, which are less separable than those of mathematics. This becomes plain if one tries [194a1] to state in each of the two cases the definitions of the things and of their attributes. Odd and even, straight and curved, and likewise number, line, and figure, do not involve motion; not so flesh and bone and man—these are defined like snub nose, [5] not like curved.
Similar evidence is supplied by the more natural of the branches of mathematics, such as optics, harmonics, and astronomy. These are in a way the converse of geometry. While geometry investigates natural lines but not qua natural, optics [10] investigates mathematical lines, but qua natural, not qua mathematical.
Since two sorts of thing are called nature, the form and the matter, we must investigate its objects as we would the essence of snubness, that is neither independently of matter nor in terms of matter only. Here too indeed one might [15] raise a difficulty. Since there are two natures, with which is the student of nature concerned? Or should he investigate the combination of the two? But if the combination of the two, then also each severally. Does it belong then to the same or to different sciences to know each severally?
If we look at the ancients, natural science would seem to be concerned with the matter. (It was only very slightly that Empedocles and Democritus touched on form [20] and essence.)
But if on the other hand art imitates nature, and it is the part of the same discipline to know the form and the matter up to a point (e.g. the doctor has a knowledge of health and also of bile and phlegm, in which health is realized and the builder both of the form of the house and of the matter, namely that it is bricks and [25] beams, and so forth): if this is so, it would be the part of natural science also to know nature in both its senses.
Again, that for the sake of which, or the end, belongs to the same department of knowledge as the means. But the nature is the end or that for the sake of which. For if a thing undergoes a continuous change toward some end, that last stage10 is [30] actually that for the sake of which. (That is why the poet was carried away into making an absurd statement when he said ‘he has the end for the sake of which he was born’. For not every stage that is last claims to be an end, but only that which is best.)
For the arts make their material (some simply make it, others make it [35] serviceable), and we use everything as if it was there for our sake. (We also are in a sense an end. ‘That for the sake of which’ may be taken in two ways, as we said in [194b1] our work On Philosophy.) The arts, therefore, which govern the matter and have knowledge are two, namely the art which uses the product and the art which directs the production of it. That is why the using art also is in a sense directive; but it differs in that it knows the form,11 whereas the art which is directive as being [5] concerned with production knows the matter. For the helmsman knows and prescribes what sort of form a helm should have, the other from what wood it should be made and by means of what operations. In the products of art, however, we make the material with a view to the function, whereas in the products of nature the matter is there all along.
Again, matter is a relative thing—for different forms there is different matter.
[10] How far then must the student of nature know the form or essence? Up to a point, perhaps, as the doctor must know sinew or the smith bronze (i.e. until he understands the purpose of each);12 and the student of nature is concerned only with things whose forms are separable indeed, but do not exist apart from matter. Man is begotten by man and by the sun as well. The mode of existence and essence of the [15] separable it is the business of first philosophy to define.
3 · Now that we have established these distinctions, we must proceed to consider causes, their character and number. Knowledge is the object of our inquiry, and men do not think they know a thing till they have grasped the ‘why’ of [20] it (which is to grasp its primary cause). So clearly we too must do this as regards both coming to be and passing away and every kind of natural change, in order that, knowing their principles, we may try to refer to these principles each of our problems.
In one way, then, that out of which a thing comes to be and which persists, is [25] called a cause, e.g. the bronze of the statue, the silver of the bowl, and the genera of which the bronze and the silver are species.
In another way, the form or the archetype, i.e. the definition of the essence, and its genera, are called causes (e.g. of the octave the relation of 2: 1, and generally number), and the parts in the definition.
[30] Again, the primary source of the change or rest; e.g. the man who deliberated is a cause, the father is cause of the child, and generally what makes of what is made and what changes of what is changed.
Again, in the sense of end or that for the sake of which a thing is done, e.g. health is the cause of walking about. (‘Why is he walking about?’ We say: ‘To be healthy’, and, having said that, we think we have assigned the cause.) The same is [35] true also of all the intermediate steps which are brought about through the action of something else as means towards the end, e.g. reduction of flesh, purging, drugs, or surgical instruments are means towards health. All these things are for the sake of [195a1] the end, though they differ from one another in that some are activities, others instruments.
This then perhaps exhausts the number of ways in which the term ‘cause’ is used.
As things are called causes in many ways, it follows that there are several causes of the same thing (not merely accidentally), e.g. both the art of the sculptor [5] and the bronze are causes of the statue. These are causes of the statue qua statue, not in virtue of anything else that it may be—only not in the same way, the one being the material cause, the other the cause whence the motion comes. Some things cause each other reciprocally, e.g. hard work causes fitness and vice versa, but again not in the same way, but the one as end, the other as the principle of [10] motion. Further the same thing is the cause of contrary results. For that which by its presence brings about one result is sometimes blamed for bringing about the contrary by its absence. Thus we ascribe the wreck of a ship to the absence of the pilot whose presence was the cause of its safety.
All the causes now mentioned fall into four familiar divisions. The letters are [15] the causes of syllables, the material of artificial products, fire and the like of bodies, the parts of the whole, and the premisses of the conclu
sion, in the sense of ‘that from which’. Of these pairs the one set are causes in the sense of what underlies, e.g. the parts, the other set in the sense of essence—the whole and the combination and the [20] form. But the seed and the doctor and the deliberator, and generally the maker, are all sources whence the change or stationariness originates, which the others are causes in the sense of the end or the good of the rest; for that for the sake of which tends to be what is best and the end of the things that lead up to it. (Whether we call [25] it good or apparently good makes no difference.)
Such then is the number and nature of the kinds of cause.
Now the modes of causation are many, though when brought under heads they too can be reduced in number. For things are called causes in many ways and even within the same kind one may be prior to another: e.g. the doctor and the expert are [30] causes of health, the relation 2: 1 and number of the octave, and always what is inclusive to what is particular. Another mode of causation is the accidental and its genera, e.g. in one way Polyclitus, in another a sculptor is the cause of a statue, because being Polyclitus and a sculptor are accidentally conjoined. Also the classes [35] in which the accidental attribute is included; thus a man could be said to be the cause of a statue or, generally, a living creature. An accidental attribute too may be [195b1] more or less remote, e.g. suppose that a pale man or a musical man were said to be the cause of the statue.
All causes, both proper and accidental, may be spoken of either as potential or as actual; e.g. the cause of a house being built is either a house-builder or a [5] house-builder building.
Similar distinctions can be made in the things of which the causes are causes, e.g. of this statue or of a statue or of an image generally, of this bronze or of bronze [10] or of material generally. So too with the accidental attributes. Again we may use a complex expression for either and say, e.g., neither ‘Polyclitus’ nor a ‘sculptor’ but ‘Polyclitus, the sculptor’.
All these various uses, however, come to six in number, under each of which again the usage is twofold. It is either what is particular or a genus, or an accidental [15] attribute or a genus of that, and these either as a complex or each by itself; and all either as actual or as potential. The difference is this much, that causes which are actually at work and particular exist and cease to exist simultaneously with their effect, e.g. this healing person with this being-healed person and that housebuilding [20] man with that being-built house; but this is not always true of potential causes—the house and the housebuilder do not pass away simultaneously.
In investigating the cause of each thing it is always necessary to seek what is most precise (as also in other things): thus a man builds because he is a builder, and a builder builds in virtue of his art of building. This last cause then is prior; and so [25] generally.
Further, generic effects should be assigned to generic causes, particular effects to particular causes, e.g. statue to sculptor, this statue to this sculptor; and powers are relative to possible effects, actually operating causes to things which are actually being effected.
This must suffice for our account of the number of causes and the modes of [30] causation.
4 · But chance and spontaneity are also reckoned among causes: many things are said both to be and to come to be as a result of chance and spontaneity. We must inquire therefore in what manner chance and spontaneity are present [35] among the causes enumerated, and whether they are the same or different, and generally what chance and spontaneity are.
Some people even question whether there are such things or not. They say that [196a1] nothing happens by chance, but that everything which we ascribe to chance or spontaneity has some definite cause, e.g. coming by chance into the market and finding there a man whom one wanted but did not expect to meet is due to one’s [5] wish to go and buy in the market. Similarly, in other so-called cases of chance it is always possible, they maintain, to find something which is the cause; but not chance, for if chance were real, it would seem strange indeed, and the question might be raised, why on earth none of the wise men of old in speaking of the causes [10] of generation and decay took account of chance; whence it would seem that they too did not believe that anything is by chance. But there is a further circumstance that is surprising. Many things both come to be and are by chance and spontaneity, and although all know that each of them can be ascribed to some cause (as the old [15] argument said which denied chance), nevertheless they all speak of some of these things as happening by chance and others not. For this reason they ought to have at least referred to the matter in some way or other.
Certainly the early physicists found no place for chance among the causes which they recognized—love, strife, mind, fire, or the like. This is strange, whether they supposed that there is no such thing as chance or whether they thought there is but omitted to mention it—and that too when they sometimes used it, as [20] Empedocles does when he says that the air is not always separated into the highest region, but as it may chance. At any rate he says in his cosmogony that ‘it happened to run that way at that time, but it often ran otherwise’.13 He tells us also that most of the parts of animals came to be by chance.
There are some who actually ascribe this heavenly sphere and all the worlds to [25] spontaneity. They say that the vortex arose spontaneously, i.e. the motion that separated and arranged the universe in its present order. This statement might well cause surprise. For they are asserting that chance is not responsible for the existence or generation of animals and plants, nature or mind or something of the kind being [30] the cause of them (for it is not any chance thing that comes from a given seed but an olive from one kind and a man from another); and yet at the same time they assert that the heavenly sphere and the divinest of visible things arose spontaneously, having no such cause as is assigned to animals and plants. Yet if this is so, it is a fact [35] which deserves to be dwelt upon, and something might well have been said about it. For besides the other absurdities of the statement, it is the more absurd that people [196b1] should make it when they see nothing coming to be spontaneously in the heavens, but much happening by chance among the things which as they say are not due to chance; whereas we should have expected exactly the opposite.
Others there are who believe that chance is a cause, but that it is inscrutable to [5] human intelligence, as being a divine thing and full of mystery.
Thus we must inquire what chance and spontaneity are, whether they are the same or different, and how they fit into our division of causes.
5 · First then we observe that some things always come to pass in the same [10] way, and others for the most part. It is clearly of neither of these that chance, or the result of chance, is said to be the cause—neither of that which is by necessity and always, nor of that which is for the most part. But as there is a third class of events besides these two—events which all say are by chance—it is plain that there is such [15] a thing as chance and spontaneity; for we know that things of this kind are due to chance and that things due to chance are of this kind.
Of things that come to be, some come to be for the sake of something, others not. Again, some of the former class are in accordance with intention, others not, but both are in the class of things which are for the sake of something. Hence it is clear that even among the things which are outside what is necessary and what is for [20] the most part, there are some in connexion with which the phrase ‘for the sake of something’ is applicable. (Things that are for the sake of something include whatever may be done as a result of thought or of nature.) Things of this kind, then, when they come to pass accidentally are said to be by chance. For just as a thing is something either in virtue of itself or accidentally, so may it be a cause. For [25] instance, the housebuilding faculty is in virtue of itself a cause of a house, whereas the pale or the musical is an accidental cause. That which is per se cause is determinate, but the accidental cause is indeterminable; for the possible attributes of an individual are innumerable. As we said, then, whe
n a thing of this kind comes [30] to pass among events which are for the sake of something, it is said to be spontaneous or by chance. (The distinction between the two must be made later—for the present it is sufficient if it is plain that both are in the sphere of things done for the sake of something.)
Example: A man is engaged in collecting14 subscriptions for a feast. He would have gone to such and such a place for the purpose of getting the money, if he had [35] known. He actually went there for another purpose, and it was only accidentally that he got his money by going there;15 and this was not due to the fact that he went [197a1] there as a rule or necessarily, nor is the end effected (getting the money) a cause present in himself—it belongs to the class of things that are objects of choice and the result of thought. It is when these conditions are satisfied that the man is said to have gone by chance. If he had chosen and gone for the sake of this—if he always or normally went there when he was collecting payments—he would not be said to [5] have gone by chance. It is clear then that chance is an accidental cause in the sphere of those actions for the sake of something which involve choice. Thought, then, and chance are in the same sphere, for choice implies thought.
It is necessary, no doubt, that the causes of what comes to pass by chance be indefinite; and that is why chance is supposed to belong to the class of the indefinite [10] and to be inscrutable to man, and why it might be thought that, in a way, nothing occurs by chance. For all these statements are correct, as might be expected. Things do, in a way, occur by chance, for they occur accidentally and chance is an accidental cause. But it is not the cause without qualification of anything; for [15] instance, a housebuilder is the cause of a house; accidentally, a fluteplayer may be so.
And the causes of the man’s coming and getting the money (when he did not come for the sake of that) are innumerable. He may have wished to see somebody or been following somebody or avoiding somebody, or may have gone to see a spectacle. Thus to say that chance is unaccountable is correct. For an account is of [20] what holds always or for the most part, whereas chance belongs to a third type of event. Hence, since causes of this kind are indefinite, chance too is indefinite. (Yet in some cases one might raise the question whether any chance fact might be the cause of the chance occurrence, e.g. of health the fresh air or the sun’s heat may be the cause, but having had one’s hair cut cannot; for some accidental causes are more relevant to the effect than others.)
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