atever things are
distinguished by the intellect are really distinct. Now as regards
incorporeal substance, the intellect apprehends that which
distinguishes it from corporeal substance, and that which it has in
common with it. Hence he concludes that what distinguishes
incorporeal from corporeal substance is a kind of form to it, and
whatever is subject to this distinguishing form, as it were something
common, is its matter. Therefore, he asserts the universal matter of
spiritual and corporeal things is the same; so that it must be
understood that the form of incorporeal substance is impressed in the
matter of spiritual things, in the same way as the form of quantity
is impressed in the matter of corporeal things.

But one glance is enough to show that there cannot be one matter of
spiritual and of corporeal things. For it is not possible that a
spiritual and a corporeal form should be received into the same part
of matter, otherwise one and the same thing would be corporeal and
spiritual. Hence it would follow that one part of matter receives the
corporeal form, and another receives the spiritual form. Matter,
however, is not divisible into parts except as regarded under
quantity; and without quantity substance is indivisible, as Aristotle
says (Phys. i, text 15). Therefore it would follow that the matter of
spiritual things is subject to quantity; which cannot be. Therefore it
is impossible that corporeal and spiritual things should have the same
matter.

It is, further, impossible for an intellectual substance to have any
kind of matter. For the operation belonging to anything is according
to the mode of its substance. Now to understand is an altogether
immaterial operation, as appears from its object, whence any act
receives its species and nature. For a thing is understood according
to its degree of immateriality; because forms that exist in matter are
individual forms which the intellect cannot apprehend as such. Hence
it must be that every individual substance is altogether immaterial.

But things distinguished by the intellect are not necessarily
distinguished in reality; because the intellect does not apprehend
things according to their mode, but according to its own mode. Hence
material things which are below our intellect exist in our intellect
in a simpler mode than they exist in themselves. Angelic substances,
on the other hand, are above our intellect; and hence our intellect
cannot attain to apprehen