The Complete Aristotle (eng.)

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.
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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