One body is said to divide another, by penetrating it. This
assertion, however, demands demonstration, for it is more reasonable
to suppose that qualities may penetrate a body without dividing
it. Such demonstration is attempted by the claim that qualities
are incorporeal.[63] But if matter itself be as incorporeal as the
qualities, why could not some qualities along with the matter penetrate
into some other body? That some solids do not penetrate other bodies,
is due to their possession of qualities incompatible with that of
penetration. The objection that many qualities could not, along with
matter, penetrate some body, would be justified only if it were the
multitude of qualities that produced density; but if density be as much
of a quality as corporeity, the qualities will constitute the mixture
not in themselves alone, but only as they happen to be determined.
On the other hand, when matter does not lend itself to mixture, this
occurs not by virtue of its being matter, but as matter united to some
determinative quality. That is all the truer as matter is receptive to
any magnitude, not having any of its own. But enough of this.