Substance, in the truest and primary and most definite sense of
the word, is that which is neither predicable of a subject nor present
in a subject; for instance, the individual man or horse. But in a
secondary sense those things are called substances within which, as
species, the primary substances are included; also those which, as
genera, include the species. For instance, the individual man is
included in the species 'man', and the genus to which the species
belongs is 'animal'; these, therefore-that is to say, the species
'man' and the genus 'animal,-are termed secondary substances.
It is plain from what has been said that both the name and the
definition of the predicate must be predicable of the subject. For
instance, 'man' is predicted of the individual man. Now in this case
the name of the species man' is applied to the individual, for we
use the term 'man' in describing the individual; and the definition of
'man' will also be predicated of the individual man, for the
individual man is both man and animal. Thus, both the name and the
definition of the species are predicable of the individual.
With regard, on the other hand, to those things which are present in
a subject, it is generally the case that neither their name nor
their definition is predicable of that in which they are present.
Though, however, the definition is never predicable, there is
nothing in certain cases to prevent the name being used. For instance,
'white' being present in a body is predicated of that in which it is
present, for a body is called white: the definition, however, of the
colour white' is never predicable of the body.
Everything except primary substances is either predicable of a
primary substance or present in a primary substance. This becomes
evident by reference to particular instances which occur. 'Animal'
is predicated of the species 'man', therefore of the individual man,
for if there were no individual man of whom it could be predicated, it
could not be predicated of the species 'man' at all. Again, colour