men, and therefore there is an Idea of man. But there is
also an element common to the individual man and to the
Idea of man. There must, therefore, be a further Idea, the
“third man,” to explain this. And between this further Idea
and the individual man there must be yet another Idea to
explain what they have in common, and so onad infinitum.
(7) But by far the most important of all Aristotle’s ob-
jections to the ideal theory, and that which, to all intents
and purposes, sums up all the others, is that it assumes
that Ideas are the essences of things, and yet places those
essences outside the things themselves. The essence of a
thing must be in it, and not outside it. But Plato separated
Ideas from things, and placed the Ideas away somewhere in
a mysterious world of their own. The Idea, as the univer-
sal, can only exist in the particular. Possibly the reality
in all horses is the universal horse, but the universal horse
is not something that exists by itself and independently
of individual horses. Hence Plato was led into the absur-
dity of talking as if, besides the individual horses we know,
there is somewhere another individual called the horse-
in-general, or as if besides white objects there is a thing
called {265} whiteness. And this is in fact the supreme
self-contradiction of the theory of Ideas, that it begins by
saying that the universal is real, and the particular unreal,
but ends by degrading the universal again into a particu-
lar. This is the same thing as saying that Plato’s mistake
lay in first (rightly) seeing that existence is not reality, but
then (wrongly) going on to imagine that the reality is an
existence.
Out of this last objection grows Aristotle’s own philosophy,
the fundamental principle of which is that the universal is
indeed the absolute reality, but that it is a universal which
exists only in the particular. What is reality? What is
substance? This is the first question for the metaphysician.
Now substance is what has an independent existence of its
own; it is that whose being does not flow into it from any
source outside itself. Consequently, substance is what is
never a predicate; it is that to which all predicates are
applied. Thus in the proposition, “Gold is heavy,” gold is
the subject, or substance, and “heavy” is its predicate. The
heaviness is dependent for its existence on the gold, and
it is therefore the latter, and not the former, that is the
substance.Now, keeping this in mind, are universals, as Plato asserts,
substances? No; because the universal is merely a com-
mon predicate which attaches to many objects of a class.
Thus the concept of man is merely what is common to
all men. It is the same thing as the predicate “humanness.”
But humanness cannot exist apart from human beings, any
more than heaviness apart from the heavy object. Univer-
sals, then, are not substances. But neither are particulars
substances. For there is no such thing as that which is ab-
solutely {266} particular and isolated. If humanness does
not exist apart from men, neither do men exist apart from
humanness. Take away from a man what he has in com-
mon with other men, and what he has in common with
other objects, and you will find that, having stripped him
of all his qualities, there is absolutely nothing left. We say
gold is heavy, yellow, malleable,etc. Now the heaviness,
the yellowness, and the other qualities, cannot exist apart