Categories   

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 every.

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,