ave seen above (Q. 55, A. 2) in the order of nature,
holds the lowest place among intellectual substances; inasmuch as it
is not naturally gifted with the knowledge of truth, as the angels
are; but has to gather knowledge from individual things by way of the
senses, as Dionysius says (Div. Nom. vii). But nature never fails in
necessary things: therefore the intellectual soul had to be endowed
not only with the power of understanding, but also with the power of
feeling. Now the action of the senses is not performed without a
corporeal instrument. Therefore it behooved the intellectual soul to
be united to a body fitted to be a convenient organ of sense.

Now all the other senses are based on the sense of touch. But the
organ of touch requires to be a medium between contraries, such as hot
and cold, wet and dry, and the like, of which the sense of touch has
the perception; thus it is in potentiality with regard to contraries,
and is able to perceive them. Therefore the more the organ of touch is
reduced to an equable complexion, the more sensitive will be the
touch. But the intellectual soul has the power of sense in all its
completeness; because what belongs to the inferior nature pre-exists
more perfectly in the superior, as Dionysius says (Div. Nom. v).
Therefore the body to which the intellectual soul is united should be
a mixed body, above others reduced to the most equable complexion. For
this reason among animals, man has the best sense of touch. And among
men, those who have the best sense of touch have the best
intelligence. A sign of which is that we observe "those who are
refined in body are well endowed in mind," as stated in _De Anima_ ii,
9.

Reply Obj. 1: Perhaps someone might attempt to answer this by saying
that before sin the human body was incorruptible. This answer does
not seem sufficient; because before sin the human body was immortal
not by nature, but by a gift of Divine grace; otherwise its
immortality would not be forfeited through sin, as neither was the
immortality of the devil.

Therefore we answer otherwise by observing that in matter two
conditions are to be found; one which is chosen in order that the
matter be suitable to the form; the other which follows by force of
the first disposition. The artisan, for instance, for the form of the
saw chooses iron adapted for cutting through hard material; but that
the teeth of the saw may become blunt and rusted, follows by force of
the matter it