Reasoning in detail in another volume of this series.

The Feelings are the mental faculties whereby we experience emotions or feelings. Feelings are the experiencing of the agreeable or disagreeable nature of our mental states. They can be defined only in their own terms. If we have never experienced a feeling, we cannot understand the words expressing it. Feelings result in what are called emotion, affection and desire. An emotion is the simple feeling, such as joy, sorrow, etc. An affection is an emotion reaching out toward another and outside object, such as envy, jealousy, love, etc. A desire is an emotion arising from the want of some lacking quality or thing, and the inclination to possess it.

Memory is the faculty of the Mind whereby we retain and reproduce, or consciously revive any kind of past mental experience. It has two sub-phases; viz., Retention and Recollection, respectively. It manifests in the storing away of mental images and ideas, and in the reproduction of them at a later period of time, and also of the recognition of them as objects of past experience.

Imagination is the faculty of the Mind whereby we represent (re-pre-sent) as a mental image some previously experienced idea, concept or image. Its activities are closely allied and blended with those of the Memory. It has the power not only of reproducing objects already perceived but also another power of ideal creation whereby it creates new combinations from the materials of past experience. It is a faculty, the importance of which is but little understood by the majority of men. Inasmuch as the mental image must always precede the material manifestation, the cultivation of the Imagination becomes a matter of great importance and worthy of the closest study.

Intuition is the faculty of the Mind whereby it evolves what have been called Primary Truths or Primary Ideas. By Primary Ideas are meant the ideas of Space, Time, Cause, Identity, etc. By Primary Truths are meant the so-called "Self-Evident Truths" of geometry, mathematics and logic. Under the head of Intuition are also sometimes included the activities of the Subconscious or Superconscious regions of the mind, of which we have spoken in detail in a volume under that name of this series. Some authorities hold to the older idea of "Innate Ideas" by which is meant that every human being is born with the knowledge of certain fundamental truths, unconnected with any experience. Others hold that these ideas are simply the result of the experience of the race, transmitted to us as "germ ideas" which must grow by experience and exercise.

That each and every faculty of the Mind may be strengthened and developed by Culture and Exercise is now held to be a fact by nearly every authority worthy of that name. Just as the physical muscle may be cultivated by the proper methods, so may the mental faculties be strengthened and cultivated by the appropriate methods and means. Inasmuch as the majority of the race are deficient in the development of one or more of the leading mental faculties, it becomes a matter of great interest and importance that all should acquaint themselves with the means whereby their deficiencies may be corrected and remedied. We shall now proceed to the consideration of Thought-Culture in general, and then to the consideration of the culture of each particular general faculty, in detail.

CHAPTER IV.

THOUGHT-CULTURE

Thought-Culture is based upon two general scientific facts which may be stated as follows:

I. The brain centres of thought may be developed by exercise. While we do not assert that the brain and the mind are identical, it is nevertheless a scientific truth that "the brain is the organ of the mind" and that one of the first requisites for a good mind is a good brain. It has been proven by experiment that the brain-cells concerned in special mental activities multiply in proportion to the active use of the special faculties employed in the mental operation. It has also been ascertained that disuse of special faculties of the mind tends to cause a process akin to atrophy in the brain-cells concerned in the particular activity, so that it becomes difficult to think clearly along those particular lines after a long period of disuse. Moreover, it is known that the education and mental culture of a child is accompanied by an increase and development of the brain-cells connected with the particular fields of thought in which the child is exercised.

There is a close analogy between the exercise of the brain-cells and the exercise of the muscles of the body. Both respond to reasonable exercise; both are injured by overwork; both degenerate by disuse. As Brooks says: "The mind grows by its own inherent energies. Mental exercise is thus the law of mental development. As a muscle grows strong by use, so any faculty of the mind is developed by its proper use and exercise. An inactive mind, like an unused muscle, becomes weak and unskilful. Hang the arm in a sling and the muscle becomes flabby and loses its vigor and skill; let the mind remain inactive and it acquires a mental flabbiness that unfits it for any severe or prolonged activity. An idle mind loses its tone and strength like an unused muscle; the mental powers go to rust through idleness and inaction. To develop the faculties of the mind and secure their highest activity and efficiency, there must be a constant and judicious exercise of these faculties. The object of culture is to stimulate and direct the activity of the mind."

Experiments conducted by scientists upon dogs have shown that in the case of dogs specially trained to unusual mental activity, there has been a corresponding increase of the number of active brain-cells in the particular parts of the brain concerned with those mental activities. Microscopic examination of the brain tissues showed the greatest difference between the brain structure of the trained dogs and untrained ones of the same brood. So carefully were the experiments conducted that it was possible to distinguish between the dogs trained in one set of activities from those trained in another. Biologists have demonstrated the correctness of the brain-cell development theory beyond reasonable doubt, and ordinary human experience also adds its testimony in its favor.

In view of the above, it will be seen that by intelligent exercise and use any and all faculties of the mind may be developed and cultivated, just as may any special muscle of the body. And this exercise can come only from actual use of the faculties themselves. Development must come from within and not from without. No system of outward stimulation will develop the faculties of the mind—they may be cultivated only by an exercise in their own particular field of work. The only way to exercise any particular faculty of thought is to think through that faculty.

II. Not only are the brain-cells developed by exercise, but it also appears to be a fact that the mind appears actually to be nourished by knowledge of the outside world of things. The raw material of thought is taken into the mind and there is digested by the thought-processes, and is afterward actually assimilated by the mind in a manner strikingly similar to the processes of the physical organs of nutrition. A mind to be at its best must be supplied with a normal amount of mental nourishment. Lacking this, it tends to become weak and inefficient. And, likewise, if its owner is a mental glutton and furnishes too much