ed of the species 'man' at all. Again, colour is present in
body, therefore in individual bodies, for if there were no individual
body in which it was present, it could not be present in body at all.
Thus everything except primary substances is either predicated of
primary substances, or is present in them, and if these last did not
exist, it would be impossible for anything else to exist.

Of secondary substances, the species is more truly substance than the
genus, being more nearly related to primary substance. For if any one
should render an account of what a primary substance is, he would
render a more instructive account, and one more proper to the subject,
by stating the species than by stating the genus. Thus, he would give a
more instructive account of an individual man by stating that he was
man than by stating that he was animal, for the former description is
peculiar to the individual in a greater degree, while the latter is too
general. Again, the man who gives an account of the nature of an
individual tree will give a more instructive account by mentioning the
species 'tree' than by mentioning the genus 'plant'.

Moreover, primary substances are most properly called substances in
virtue of the fact that they are the entities which underlie everything
else, and that everything else is either predicated of them or present
in them. Now the same relation which subsists between primary substance
and everything else subsists also between the species and the genus:
for the species is to the genus as subject is to predicate, since the
genus is predicated of the species, whereas the species cannot be
predicated of the genus. Thus we have a second ground for asserting
that the species is more truly substance than the genus.

Of species themselves, except in the case of such as are genera, no one
is more truly substance than another. We should not give a more
appropriate account of the individual man by stating the species to
which he belonged, than we should of an individual horse by adopting
the same method of definition. In the same way, of primary substances,
no one is more truly substance than another; an individual man is not
more truly substance than an individual ox.

It is, then, with good reason that of all that remains, when we exclude
primary substances, we concede to species and genera alone the name
'secondary substance', for these alone of all the predicates convey a
knowledge of primary substance. F