the soul desires some particular desirable thing--namely its
own suitable object. Therefore, with regard to this object which is
the desirable in general, we should not assign some particular power
distinct from the others, called the appetitive power.

_On the contrary,_ The Philosopher distinguishes (De Anima ii, 3) the
appetitive from the other powers. Damascene also (De Fide Orth. ii,
22) distinguishes the appetitive from the cognitive powers.

_I answer that,_ It is necessary to assign an appetitive power to the
soul. To make this evident, we must observe that some inclination
follows every form: for example, fire, by its form, is inclined to
rise, and to generate its like. Now, the form is found to have a more
perfect existence in those things which participate knowledge than in
those which lack knowledge. For in those which lack knowledge, the
form is found to determine each thing only to its own being--that is,
to its nature. Therefore this natural form is followed by a natural
inclination, which is called the natural appetite. But in those things
which have knowledge, each one is determined to its own natural being
by its natural form, in such a manner that it is nevertheless
receptive of the species of other things: for example, sense receives
the species of all things sensible, and the intellect, of all things
intelligible, so that the soul of man is, in a way, all things by
sense and intellect: and thereby, those things that have knowledge, in
a way, approach to a likeness to God, "in Whom all things pre-exist,"
as Dionysius says (Div. Nom. v).

Therefore, as forms exist in those things that have knowledge in a
higher manner and above the manner of natural forms; so must there be
in them an inclination surpassing the natural inclination, which is
called the natural appetite. And this superior inclination belongs to
the appetitive power of the soul, through which the animal is able to
desire what it apprehends, and not only that to which it is inclined
by its natural form. And so it is necessary to assign an appetitive
power to the soul.

Reply Obj. 1: Appetite is found in things which have knowledge, above
the common manner in which it is found in all things, as we have said
above. Therefore it is necessary to assign to the soul a particular
power.

Reply Obj. 2: What is apprehended and what is desired are the same in
reality, but differ in aspect: for a thing is apprehended as
something sensible or i