Abstract
Book 1 of Aristotle’s De Anima extensively discusses two characteristics of the soul: the soul as the source of motion of the living being, and the soul as the seat of perception and cognition. The following conclusions are drawn on the nature and function of the soul. The soul is not a magnitude and not material; it is a substance and not an attribute; it is a unity, and the principle of unity is not material continuity. The soul is the origin of perception and motion, and of psychological processes such as emotions and desires. An adequate account of how the soul causes perception, motion, and the like must not attribute motion to the soul.