By being 'present in a subject' I do not mean present as parts are
present in a whole, but being incapable of existence apart from the
Some things, again, are present in a subject, but are never
predicable of a subject. For instance, a certain point of
grammatical knowledge is present in the mind, but is not predicable of
any subject; or again, a certain whiteness may be present in the
body (for colour requires a material basis), yet it is never
predicable of anything.
Other things, again, are both predicable of a subject and present in
a subject. Thus while knowledge is present in the human mind, it is
predicable of grammar.
There is, lastly, a class of things which are neither present in a
subject nor predicable of a subject, such as the individual man or the
individual horse. But, to speak more generally, that which is
individual and has the character of a unit is never predicable of a
subject. Yet in some cases there is nothing to prevent such being
present in a subject. Thus a certain point of grammatical knowledge is
present in a subject.
When one thing is predicated of another, all that which is
predicable of the predicate will be predicable also of the subject.
Thus, 'man' is predicated of the individual man; but 'animal' is
predicated of 'man'; it will, therefore, be predicable of the
individual man also: for the individual man is both 'man' and
If genera are different and co-ordinate, their differentiae are
themselves different in kind. Take as an instance the genus 'animal'
and the genus 'knowledge'. 'With feet', 'two-footed', 'winged',