The Complete Aristotle (eng.)

units,
as is said by some; for two is either not one, or there is no unit
present in it in complete reality. But our result involves a
difficulty. If no substance can consist of universals because a
universal indicates a ‘such’, not a ‘this’, and if no substance can
be composed of substances existing in complete reality, every
substance would be incomposite, so that there would not even be a
formula of any substance. But it is thought by all and was stated
long ago that it is either only, or primarily, substance that can
defined; yet now it seems that not even substance can. There
cannot, then, be a definition of anything; or in a sense there can
be, and in a sense there cannot. And what we are saying will be
plainer from what follows.
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    It is clear also from these very facts what consequence
confronts those who say the Ideas are substances capable of
separate existence, and at the same time make the Form consist of
the genus and the differentiae. For if the Forms exist and ‘animal’
is present in ‘man’ and ‘horse’, it is either one and the same in
number, or different. (In formula it is clearly one; for he who
states the formula will go through the formula in either case.) If
then there is a ‘man-in-himself’ who is a ‘this’ and exists apart,
the parts also of which he consists, e.g. ‘animal’ and
‘two-footed’, must indicate ‘thises’, and be capable of separate
existence, and substances; therefore ‘animal’, as well as ‘man’,
must be of this sort.
    Now (1) if the ‘animal’ in ‘the horse’ and in ‘man’ is one and
the same, as you are with yourself, (a) how will the one in things
that exist apart be one, and how will this ‘animal’ escape being
divided even from itself?
    Further, (b) if it is to share in ‘two-footed’ and
‘many-footed’, an impossible conclusion follows; for contrary
attributes will belong at the same time to it although it is one
and a ‘this’. If it is not to share in them, what is the relation
implied when one says the animal is two-footed or possessed of
feet? But perhaps the two things are ‘put together’ and are ‘in
contact’, or are ‘mixed’. Yet all these expressions are absurd.
    But (2) suppose the Form to be different in each species. Then
there will be practically an infinite number of things whose
substance is animal’; for it is not by accident that ‘man’ has
‘animal’ for one of its elements. Further, many things will be
‘animal-itself’. For (i) the ‘animal’ in each species will be the
substance of the species; for it is after nothing else that the
species is called; if it were, that other would be an element in
‘man’, i.e. would be the genus of man. And further, (ii) all the
elements of which ‘man’ is composed will be Ideas. None of them,
then, will be the Idea of one thing and the substance of another;
this is impossible. The ‘animal’, then, present in each species of
animals will be animal-itself. Further, from what is this ‘animal’
in each species derived, and how will it be derived from
animal-itself? Or how can this ‘animal’, whose essence is simply
animality, exist apart from animal-itself?
    Further, (3)in the case of sensible things both these
consequences and others still more absurd follow. If, then, these
consequences are impossible, clearly there are not Forms of
sensible things in the sense in which some maintain their
existence.
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    Since substance is of two kinds, the concrete thing and the
formula (I mean that one kind of substance is the formula taken
with the matter, while another kind is the formula in its
generality), substances in the former sense are capable of
destruction (for they are capable also of generation), but there is
no destruction of the formula in the sense that it is ever in
course of being destroyed (for there is no generation of it either;
the being of house is not generated, but only the being of this
house), but without generation and destruction formulae are and are
not; for it has been shown that no one begets nor makes these. For
this reason, also, there is neither definition of nor demonstration
about sensible individual substances, because they have matter
whose nature is such that they are capable both of being and of not
being; for which reason all the individual instances of them are
destructible. If then demonstration is of