self. So the intellectual soul requires a body of equable
complexion, which, however, is corruptible by force of its matter. If,
however, it be said that God could avoid this, we answer that in the
formation of natural things we do not consider what God might do; but
what is suitable to the nature of things, as Augustine says (Gen. ad
lit. ii, 1). God, however, provided in this case by applying a remedy
against death in the gift of grace.

Reply Obj. 2: A body is not necessary to the intellectual soul by
reason of its intellectual operation considered as such; but on
account of the sensitive power, which requires an organ of equable
temperament. Therefore the intellectual soul had to be united to such
a body, and not to a simple element, or to a mixed body, in which
fire was in excess; because otherwise there could not be an
equability of temperament. And this body of an equable temperament
has a dignity of its own by reason of its being remote from
contraries, thereby resembling in a way a heavenly body.

Reply Obj. 3: The parts of an animal, for instance, the eye, hand,
flesh, and bones, and so forth, do not make the species; but the
whole does, and therefore, properly speaking, we cannot say that
these are of different species, but that they are of various
dispositions. This is suitable to the intellectual soul, which,
although it be one in its essence, yet on account of its perfection,
is manifold in power: and therefore, for its various operations it
requires various dispositions in the parts of the body to which it is
united. For this reason we observe that there is a greater variety of
parts in perfect than in imperfect animals; and in these a greater
variety than in plants.

Reply Obj. 4: The intellectual soul as comprehending universals, has
a power extending to the infinite; therefore it cannot be limited by
nature to certain fixed natural notions, or even to certain fixed
means whether of defence or of clothing, as is the case with other
animals, the souls of which are endowed with knowledge and power in
regard to fixed particular things. Instead of all these, man has by
nature his reason and his hands, which are "the organs of organs" (De
Anima iii), since by their means man can make for himself instruments
of an infinite variety, and for any number of purposes.
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SIXTH ARTICLE [I, Q. 76, Art. 6]

Whether the Intellectual Soul Is United to the Body Through the Medium
of Accident