Summa Theologica

We now have to consider the acts of the soul in regard to the intellectual and the appetitive powers: for the other powers of the soul do not come directly under the consideration of the theologian. Furthermore, the acts of the appetitive part of the soul come under the consideration of the science of morals; wherefore we shall treat of them in the second part of this work, to which the consideration of moral matters belongs. But of the acts of the intellectual part we shall treat now.

In treating of these acts we shall proceed in the following order: First, we shall inquire how the soul understands when united to the body; secondly, how it understands when separated therefrom.

The former of these inquiries will be threefold: (1) How the soul understands bodies which are beneath it; (2) How it understands itself and things contained in itself; (3) How it understands immaterial substances, which are above it.

In treating of the knowledge of corporeal things there are three points to be considered: (1) Through what does the soul know them? (2) How and in what order does it know them? (3) What does it know in them?

Under the first head there are eight points of inquiry:

(1) Whether the soul knows bodies through the intellect?

(2) Whether it understands them through its essence, or through any species?

(3) If through some species, whether the species of all things intelligible are naturally innate in the soul?

(4) Whether these species are derived by the soul from certain separate immaterial forms?

(5) Whether our soul sees in the eternal ideas all that it understands?

(6) Whether it acquires intellectual knowledge from the senses?

(7) Whether the intellect can, through the species of which it is possessed, actually understand, without turning to the phantasms?

(8) Whether the judgment of the intellect is hindered by an obstacle in the sensitive powers?