ong the powers of the soul.

Obj. 3: Further, where there is order among powers, we find that the
operation of one depends on the operation of another. But the action
of one power of the soul does not depend on that of another; for
sight can act independently of hearing, and conversely. Therefore
there is no order among the powers of the soul.

_On the contrary,_ The Philosopher (De Anima ii, 3) compares the parts
or powers of the soul to figures. But figures have an order among
themselves. Therefore the powers of the soul have order.

_I answer that,_ Since the soul is one, and the powers are many; and
since a number of things that proceed from one must proceed in a
certain order; there must be some order among the powers of the soul.
Accordingly we may observe a triple order among them, two of which
correspond to the dependence of one power on another; while the third
is taken from the order of the objects. Now the dependence of one
power on another can be taken in two ways; according to the order of
nature, forasmuch as perfect things are by their nature prior to
imperfect things; and according to the order of generation and time;
forasmuch as from being imperfect, a thing comes to be perfect. Thus,
according to the first kind of order among the powers, the
intellectual powers are prior to the sensitive powers; wherefore they
direct them and command them. Likewise the sensitive powers are prior
in this order to the powers of the nutritive soul.

In the second kind of order, it is the other way about. For the powers
of the nutritive soul are prior by way of generation to the powers of
the sensitive soul; for which, therefore, they prepare the body. The
same is to be said of the sensitive powers with regard to the
intellectual. But in the third kind of order, certain sensitive powers
are ordered among themselves, namely, sight, hearing, and smelling.
For the visible naturally comes first; since it is common to higher
and lower bodies. But sound is audible in the air, which is naturally
prior to the mingling of elements, of which smell is the result.

Reply Obj. 1: The species of a given genus are to one another as
before and after, like numbers and figures, if considered in their
nature; although they may be said to be simultaneous, according as
they receive the predication of the common genus.

Reply Obj. 2: This order among the powers of the soul is both on the
part of the soul (which, though it be one accordin