Chapter 4: Psychological Investigation of Man and the Animal

The study of the human body leads us to the study of the indwelling soul, in which we find the reason for the skill and appropriateness of the body, and the reason for the works and achievements of man; for no matter how much we examine the powers and activities of man, it is impossible to explain them without the guidance of some rational power. The necessity imposed by the facts compels the researcher to accept a real principle of spiritual life, which, though closely united with the body, nevertheless differs from it and is wholly independent of it. Consciousness, self-consciousness, awareness of oneself, concepts, spiritual desires, love of the good, the beneficial, the true, the useful, aversion to evil, the distinction between good and evil, and all the remaining apparent spiritual activity are testimony to the existence of the soul and its rationality.

These activities of the soul, though most varied, are divided and brought into three general types: cognitions, feelings, and desires, for all that happens in the soul is subsumed under these categories. Since these activities presume active powers, they are reduced to three chief or general powers; the cognitive, the emotional, and the volitional or appetitive. These are the characteristics of the rational soul of man. Since also animals are ascribed a soul, let us also examine the activities of animals and see, advancing the examination of the powers of each, if we can ascribe the same categories to the animal soul.