Categories, Section 1, Part 3

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 'animal'.

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', 'aquatic',
are differentiae of 'animal'; the species of knowledge are not distinguished
by the same differentiae. One species of knowledge does not differ
from another in being 'two-footed'.

But where one genus is subordinate to another, there is nothing to
prevent their having the same differentiae: for the greater class
is predicated of the lesser, so that all the differentiae of the predicate
will be differentiae also of the subject.