II. KNOWLEDGE OF HUMAN NATURE.
1. The Microcosm.
Man is the noblest creature in the visible world. He unites in himself the existence of the mineral, the life of the vegetable, and the sense of the animal kingdom, and participates in the spirit-world as well by having a soul that is made to the image and likeness of God. As a spirit the soul is naturally immortal.
The faculties of the soul correspond to man's complex nature. They are (1) the nutritive, augmentative, and reproductive faculties of vegetative life; (2) the sensitive, appetitive, and locomotive faculties of animal life; (3) the intelligence, reason, and free-will of a spiritual being.
Corresponding to the vegetative and sensitive faculties of the soul are certain members of the body called organs, by means of which these faculties operate. The sensitive faculties together with their organs are called senses. Man has five external senses by which he communicates with the outside world. They are: sight, hearing, taste, smell, and touch. Man has also four internal senses that serve as a medium between the external senses and the intellectual faculties. They are: central sense, instinct, imagination, and memory. The central sense impresses the sensations of the external senses on the imagination and records them in the memory. The instinct apprehends what is fit and what unfit for the needs of animal life and arouses the appetitive faculties accordingly. The imagination forms images of natural impressions and stores them in the memory. The memory retains these images indefinitely.
Besides the vegetative and sensitive faculties man also has the appetitive and locomotive faculties common to all members of the animal kingdom. The appetitive faculty reaches out to enjoy, or to seek an attainable good, and to repel, or to escape from a threatening evil. It is aroused by the instinct through the imagination, or directly by the will, causes a corresponding disturbance in man's physical nature, and easily excites his intellectual faculties. A movement of the appetitive faculty is called a passion, feeling, or emotion. The passions are divided into concupiscible and irascible, according as their object is agreeable or repugnant in itself, or apprehended as subject to some condition of difficulty or danger. There are six of the former and five of the latter. They are: love, hatred, desire, aversion, joy, and sadness; hope, despair, courage, fear, and anger. Of these eleven the passions of fear, desire, and love exercise the greatest influence in our daily lives.
The locomotive faculty is the power of moving the limbs as well as the entire body from place to place. It is set in operation and directed by the appetitive faculty, or by the power of the will.
By his spiritual powers man rises above the material world in which he lives. The intellect abstracts ideas from the impressions made on the imagination and recorded in the memory. Reason perceives and judges what is true, good, and beautiful, and commands the will to act in accordance with its decision. The will consults the reason in regard to the propriety and manner of action, controls the other faculties, and directs them in accordance with the dictates of reason, whenever it is not hampered by the passions.