The Complete Aristotle (eng.)

to the essence of
horse there will belong a second essence. Yet why should not some
things be their essences from the start, since essence is
substance? But indeed not only are a thing and its essence one, but
the formula of them is also the same, as is clear even from what
has been said; for it is not by accident that the essence of one,
and the one, are one. Further, if they are to be different, the
process will go on to infinity; for we shall have (1) the essence
of one, and (2) the one, so that to terms of the former kind the
same argument will be applicable.
    Clearly, then, each primary and self-subsistent thing is one and
the same as its essence. The sophistical objections to this
position, and the question whether Socrates and to be Socrates are
the same thing, are obviously answered by the same solution; for
there is no difference either in the standpoint from which the
question would be asked, or in that from which one could answer it
successfully. We have explained, then, in what sense each thing is
the same as its essence and in what sense it is not.
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7
    Of things that come to be, some come to be by nature, some by
art, some spontaneously. Now everything that comes to be comes to
be by the agency of something and from something and comes to be
something. And the something which I say it comes to be may be
found in any category; it may come to be either a ‘this’ or of some
size or of some quality or somewhere.
    Now natural comings to be are the comings to be of those things
which come to be by nature; and that out of which they come to be
is what we call matter; and that by which they come to be is
something which exists naturally; and the something which they come
to be is a man or a plant or one of the things of this kind, which
we say are substances if anything is-all things produced either by
nature or by art have matter; for each of them is capable both of
being and of not being, and this capacity is the matter in
each-and, in general, both that from which they are produced is
nature, and the type according to which they are produced is nature
(for that which is produced, e.g. a plant or an animal, has a
nature), and so is that by which they are produced—the so-called
‘formal’ nature, which is specifically the same (though this is in
another individual); for man begets man.
    Thus, then, are natural products produced; all other productions
are called ‘makings’. And all makings proceed either from art or
from a faculty or from thought. Some of them happen also
spontaneously or by luck just as natural products sometimes do; for
there also the same things sometimes are produced without seed as
well as from seed. Concerning these cases, then, we must inquire
later, but from art proceed the things of which the form is in the
soul of the artist. (By form I mean the essence of each thing and
its primary substance.) For even contraries have in a sense the
same form; for the substance of a privation is the opposite
substance, e.g. health is the substance of disease (for disease is
the absence of health); and health is the formula in the soul or
the knowledge of it. The healthy subject is produced as the result
of the following train of thought:-since this is health, if the
subject is to be healthy this must first be present, e.g. a uniform
state of body, and if this is to be present, there must be heat;
and the physician goes on thinking thus until he reduces the matter
to a final something which he himself can produce. Then the process
from this point onward, i.e. the process towards health, is called
a ‘making’. Therefore it follows that in a sense health comes from
health and house from house, that with matter from that without
matter; for the medical art and the building art are the form of
health and of the house, and when I speak of substance without
matter I mean the essence.
    Of the productions or processes one part is called thinking and
the other making,-that which proceeds from the starting-point and
the form is thinking, and that which proceeds from the final step
of the thinking is making. And each of the other, intermediate,
things is produced in the same way. I mean, for instance, if the
subject is to be healthy his bodily state must be made uniform.
What then does being made uniform imply? This or that. And this
depends on his being made warm. What does this imply? Something
else. And this something is present potentially; and what