Aquinas believed what Aristotle never dreamed: that man is more than
a composite of body and soul, that his is nothing less than elevated
to a supernatural order which participates, as far as a creature can,
in the' very nature of God. Accordingly a person in the state of
grace, or divine friendship, possesses certain enduring powers, the
infused virtues and gifts, that raise him to an orbit of existence as
far above nature as heaven is above earth, and that give him
abilities of thought and operation that are literally born, not of
the will of flesh nor of the will of man, but of God. Nowhere else
does the true character of the supernatural appear more evident than
in the endowments of infused virtue which some people possess and
others do not, and that make some capable of spiritual actions which
others cannot perform.

In the Thomistic system, the soul is the substantial form of the
body, which gives man all that is properly human and places him
essentially into the natural order; sanctifying grace or
justification, by analogy, is the accidental form of the soul, which
gives the same man all that is properly divine and puts him
habitually into the family of God. Comparing the two with each
other, the soul is the foundation of natural existence, as
sanctifying grace is the principle of supernatural life.

Yet we know that the soul is not all we have in the body, that the
soul itself has powers through which it operates and by which it
gives expression to its rational nature. Even so, by a divine
consistency, the "soul of the soul," as sanctifying grace has been
called, must have channels for the deiform life that God confers on
the just. They are the virtues, theological and moral, according to
their respective purposes; not unlike the native abilities through
which mind and will come into contact with us.