The Complete Aristotle (eng.)

the
elements, but only the elements.
    (b) Again, the elements will not be even knowable; for they are
not universal, and knowledge is of universals. This is clear from
demonstrations and from definitions; for we do not conclude that
this triangle has its angles equal to two right angles, unless
every triangle has its angles equal to two right angles, nor that
this man is an animal, unless every man is an animal.
    But if the principles are universal, either the substances
composed of them are also universal, or non-substance will be prior
to substance; for the universal is not a substance, but the element
or principle is universal, and the element or principle is prior to
the things of which it is the principle or element.
    All these difficulties follow naturally, when they make the
Ideas out of elements and at the same time claim that apart from
the substances which have the same form there are Ideas, a single
separate entity. But if, e.g. in the case of the elements of
speech, the a’s and the b’s may quite well be many and there need
be no a-itself and b-itself besides the many, there may be, so far
as this goes, an infinite number of similar syllables. The
statement that an knowledge is universal, so that the principles of
things must also be universal and not separate substances, presents
indeed, of all the points we have mentioned, the greatest
difficulty, but yet the statement is in a sense true, although in a
sense it is not. For knowledge, like the verb ‘to know’, means two
things, of which one is potential and one actual. The potency,
being, as matter, universal and indefinite, deals with the
universal and indefinite; but the actuality, being definite, deals
with a definite object, being a ‘this’, it deals with a ‘this’. But
per accidens sight sees universal colour, because this individual
colour which it sees is colour; and this individual a which the
grammarian investigates is an a. For if the principles must be
universal, what is derived from them must also be universal, as in
demonstrations; and if this is so, there will be nothing capable of
separate existence-i.e. no substance. But evidently in a sense
knowledge is universal, and in a sense it is not.

Book XIV
    Translated by W. D. Ross
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1
    Regarding this kind of substance, what we have said must be
taken as sufficient. All philosophers make the first principles
contraries: as in natural things, so also in the case of
unchangeable substances. But since there cannot be anything prior
to the first principle of all things, the principle cannot be the
principle and yet be an attribute of something else. To suggest
this is like saying that the white is a first principle, not qua
anything else but qua white, but yet that it is predicable of a
subject, i.e. that its being white presupposes its being something
else; this is absurd, for then that subject will be prior. But all
things which are generated from their contraries involve an
underlying subject; a subject, then, must be present in the case of
contraries, if anywhere. All contraries, then, are always
predicable of a subject, and none can exist apart, but just as
appearances suggest that there is nothing contrary to substance,
argument confirms this. No contrary, then, is the first principle
of all things in the full sense; the first principle is something
different.
    But these thinkers make one of the contraries matter, some
making the unequal which they take to be the essence of
plurality-matter for the One, and others making plurality matter
for the One. (The former generate numbers out of the dyad of the
unequal, i.e. of the great and small, and the other thinker we have
referred to generates them out of plurality, while according to
both it is generated by the essence of the One.) For even the
philosopher who says the unequal and the One are the elements, and
the unequal is a dyad composed of the great and small, treats the
unequal, or the great and the small, as being one, and does not
draw the distinction that they are one in definition, but not in
number. But they do not describe rightly even the principles which
they call elements, for some name the great and the small with the
One and treat these three as elements of numbers, two being matter,
one the form; while others name the many and few, because the great
and the small are more appropriate in their nature to magnitude
than to number; and others name rather the universal