Not only all writers on mental science, but the most common writers and speakers, recognize a general division of mental operations, which is expressed by the terms intellect, feeling, and choice. We think, we feel, and we choose. Even the young child learns to comprehend these three grand divisions of the mental phenomena.
To this most general division, in this work, are applied the terms the intellectual powers, the susceptibilities, and the will. These terms are selected because they are the most common ones.
THE INTELLECTUAL POWERS.
Under the general class of intellectual powers are arranged the following specific powers of mind:
Sensation, Perception, Conception, Memory, Imagination, Judgment, Abstraction, Attention, and Association.
Sensation is a state of mind produced by material objects acting on the senses.
Thus, when light, which is considered as one kind of matter, affects the eye, the sensation of sight is produced. When the perfume of a rose, which is another species of matter, affects the nostrils, the sensation of smell is produced. When a bell or some musical instrument causes the air to vibrate on the drum of the ear, it causes the sensation of sound. When any sapid body is applied to the tongue, the sensation of taste is caused. When the hand, or any part of the body, comes in contact with another body, the sensation of touch is produced.
Thus it appears that the five senses are the organs of sensation, and that through their instrumentality material things operate upon the mind.
Perception is a sensation attended by the belief of a cause, and it is this additional circumstance alone which distinguishes perception from sensation.
If a person were asleep, and should suffer from the prick of a pin, or be disturbed by an unpleasant sound, these would be mere sensations, because the mind would not ascribe them to any cause. But if the person should waken, these sensations would immediately become perceptions, because they would be attended by the belief of some cause.