alone, which can be
the subject of an accident, forasmuch as it has something of
potentiality, as we have said above (A. 1, ad 6); or else this subject
is the composite. Now the composite is actual by the soul. Whence it
is clear that all the powers of the soul, whether their subject be the
soul alone, or the composite, flow from the essence of the soul, as
from their principle; because it has already been said that the
accident is caused by the subject according as it is actual, and is
received into it according as it is in potentiality.

Reply Obj. 1: From one simple thing many things may proceed
naturally, in a certain order; or again if there be diversity of
recipients. Thus, from the one essence of the soul many and various
powers proceed; both because order exists among these powers; and
also by reason of the diversity of the corporeal organs.

Reply Obj. 2: The subject is both the final cause, and in a way the
active cause, of its proper accident. It is also as it were the
material cause, inasmuch as it is receptive of the accident. From
this we may gather that the essence of the soul is the cause of all
its powers, as their end, and as their active principle; and of some
as receptive thereof.

Reply Obj. 3: The emanation of proper accidents from their subject is
not by way of transmutation, but by a certain natural resultance;
thus one thing results naturally from another, as color from light.
_______________________

SEVENTH ARTICLE [I, Q. 77, Art. 7]

Whether One Power of the Soul Arises from Another?

Objection 1: It would seem that one power of the soul does not arise
from another. For if several things arise together, one of them does
not arise from another. But all the powers of the soul are created at
the same time with the soul. Therefore one of them does not arise from
another.

Obj. 2: Further, the power of the soul arises from the soul as an
accident from the subject. But one power of the soul cannot be the
subject of another; because nothing is the accident of an accident.
Therefore one power does not arise from another.

Obj. 3: Further, one opposite does not arise from the other opposite;
but everything arises from that which is like it in species. Now the
powers of the soul are oppositely divided, as various species.
Therefore one of them does not proceed from another.

_On the contrary,_ Powers are known by their actions. But the action
of one power is caused by the action of another