We next treat of the powers of the soul specifically. The theologian, however, has only to inquire specifically concerning the intellectual and appetitive powers, in which the virtues reside. And since the knowledge of these powers depends to a certain extent on the other powers, our consideration of the powers of the soul taken specifically will be divided into three parts: first, we shall consider those powers which are a preamble to the intellect; secondly, the intellectual powers; thirdly, the appetitive powers.
Under the first head there are four points of inquiry:
(1) The powers of the soul considered generally;
(2) The various species of the vegetative part;
(3) The exterior senses;
(4) The interior senses.