Aristotle

by Various Works [lit]

  than when it exists potentially. Again man is born from man, but not

  bed from bed. That is why people say that the figure is not the nature

  of a bed, but the wood is-if the bed sprouted not a bed but wood would

  come up. But even if the figure is art, then on the same principle the

  shape of man is his nature. For man is born from man.

  We also speak of a thing's nature as being exhibited in the

  process of growth by which its nature is attained. The 'nature' in

  this sense is not like 'doctoring', which leads not to the art of

  doctoring but to health. Doctoring must start from the art, not lead

  to it. But it is not in this way that nature (in the one sense) is

  related to nature (in the other). 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', it should be added, are in two senses. For the

  privation too is in a way form. But whether in unqualified coming to

  be there is privation, i.e. a contrary to what comes to be, 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

  physicist. Obviously physical bodies contain surfaces and volumes,

  lines and points, and these are the subject-matter of mathematics.

  Further, is astronomy different from physics or a department of

  it? It seems absurd that the physicist 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 physics obviously do

  discuss their shape also and whether the earth and the 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 physical

  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, though they are not aware of it; for they

  separate the objects of physics, which are less separable than those

  of mathematics. This becomes plain if one tries 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', not like 'curved'.

  Similar evidence is supplied by the more physical of the branches of

  mathematics, such as optics, harmonics, and astronomy. These are in

  a way the converse of geometry. While geometry investigates physical

  lines but not qua physical, optics investigates mathematical lines,

  but qua physical, not qua mathematical.

  Since 'nature' has two senses, the form and the matter, we must

  investigate its objects as we would the essence of snubness. That

  is, such things are neither independent of matter nor can be defined

  in terms of matter only. Here too indeed one might raise a difficulty.

  Since there are two natures, with which is the physicist 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, physics would to be concerned with the

  matter. (It was only very slightly that Empedocles and Democritus

  touched on the forms and the 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

  beams, and so forth): if this is so, it would be the part of physics

  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 and there is a stage which is last, this stage is the end or

  '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 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' has

  two senses: the distinction is made in 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, whereas the art

  which is directive as being 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 term: to each form there corresponds a

  special matter. How far then must the physicist 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):

  and the physicist 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 separable it is the business of the primary type of

  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 (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 physical change, in order that,

  knowing their principles, we may try to refer to these principles each

  of our problems.

  In one sense, then, (1) that out of which a thing comes to be and

  which persists, is called '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 sense (2) the form or the archetype, i.e. the statement

  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.

  Again (3) the primary source of the change or coming to rest; e.g.

  the man who gave advice is a cause, the father is cause of the

  child, and generally what makes of what is made and what causes change

  of what is changed.

  Again (4) 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 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' 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 the word has several senses, it follows that there are several

  causes of the same thing not merely in virtue of a concomitant

  attribute), e.g. both the art of the sculptor 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 origin of change. 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 the causes of syllables, the material of artificial

  products, fire, c., of bodies, the parts of the whole, and the

  premisses of the conclusion, in the sense of 'that from which'. Of

  these pairs the one set are causes in the sense of substratum, e.g.

  the parts, the other set in the sense of essence-the whole and the

  combination and the form. But the seed and the doctor and the adviser,

  and generally the maker, are all sources whence the change or

  stationariness originates, while the others are causes in the sense of

  the end or the good of the rest; for 'that for the sake of which'

  means what is best and the end of the things that lead up to it.

  (Whether we say the 'good itself or the 'apparent 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 'cause' is used in many

  senses and even within the same kind one may be prior to another (e.g.

  the doctor and the expert are 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 incidental and its

  genera, e.g. in one way 'Polyclitus', in another 'sculptor' is the

  cause of a statue, because 'being Polyclitus' and 'sculptor' are

  incidentally conjoined. Also the classes in which the incidental

  attribute is included; thus 'a man' could be said to be the cause of a

  statue or, generally, 'a living creature'. An incidental attribute too

  may be 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 incidental, may be spoken of either as

  potential or as actual; e.g. the cause of a house being built is

  either 'house-builder' or 'house-builder building'.

  Similar distinctions can be made in the things of which the causes

  are causes, e.g. of 'this statue' or of 'statue' or of 'image'

  generally, of 'this bronze' or of 'bronze' or of 'material' generally.

  So too with the incidental attributes. Again we may use a complex

  expression for either and say, e.g. neither 'Polyclitus' nor

  'sculptor' but 'Polyclitus, sculptor'.

  All these various uses, however, come to six in number, under each

  of which again the usage is twofold. Cause means either what is

  particular or a genus, or an incidental attribute or a genus of

  that, and these either as a complex or each by itself; and all six

  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 house-building 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 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 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 causation.

  4

  But chance also and spontaneity are 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 among the causes enumerated, and whether

  they are the same or different, and generally what chance and

  spontaneity are.

  Some people even question whether they are real or not. They say

  that 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 wish to go and buy in the

  market. Similarly in other 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 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 know that

  each of them can be ascribed to some cause (as the old argument said

  which denied chance), nevertheless they speak of some of these

  things as happening by chance and others not. For this reason also

  they ou
ght 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 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.' He tells us also that most of the parts of animals came to

  be by chance.

  There are some too who ascribe this heavenly sphere and all the

  worlds to spontaneity. They say that the vortex arose spontaneously,

  i.e. the motion that separated and arranged in its present order all

  that exists. 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 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 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 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.