I shall conclude this chapter with a few rules relating to mental exercise, and the development and culture of the mind and brain. It is a law of the animal economy that two classes of functions can not be called into vigorous action at the same time without one or the other, or both, sooner or later sustaining injury. Hence the important rule never to enter upon continued mental exertion or to rouse deep feeling immediately after a full meal, otherwise the activity of the brain is sure to interfere with that of the stomach, and disorder its functions. Even in a perfectly healthy person, unwelcome news, sudden anxiety, or mental excitement, occurring after eating, will put an entire stop to digestion, and cause the stomach to loathe the sight of food. In accordance with this rule, we learn by experience that the very worst forms of indigestion and nervous depression are those which arise from excessive mental application, or turmoil of feeling and distraction of mind, conjoined with unrestrained indulgence in the pleasures of the table. In such circumstances, the stomach and brain react upon and disturb each other, till all the horrors of nervous disease make their unwelcome appearance, and render life miserable. The tendency to inactivity and sleep, which besets most animals after a full meal, shows repose to be, in such circumstances, the evident intention of Nature. The bad effects of violating this rule, although not in all cases immediately apparent, will most assuredly be manifest at a period less or more remote.
Dr. Caldwell, who has devoted much time and talent to the diffusion of sound physiological information and the general improvement of the race, and whose opportunities of observation have been very extensive, expressly states, that dyspepsy and madness prevail more extensively in the United States than among the people of any other nation. Of the amount of our dyspeptics, he says, no estimate can be formed; but it is immense. Whether we inquire in cities, towns, villages, or country places; among the rich, the poor, or those in moderate circumstances, we find dyspepsy more or less prevalent throughout the land.
The early part of the day is the best time for severe mental exertion. Nature has allotted the darkness of night for repose, and for the restoration by sleep of the exhausted energies of both body and mind. If study or composition be ardently engaged in toward the close of the day, and especially at a late hour of the evening, sound and invigorating sleep may not be expected until the night is far spent, for the increased action of the brain which always accompanies activity of mind requires a long time to subside. Persons who practice night study, if they be at all of an irritable habit of body, will be sleepless for hours after going to bed, and be tormented perhaps by unpleasant dreams, which will render their sleep unrefreshing. If this practice be long continued, the want of refreshing repose will ultimately induce a state of morbid irritability of the nervous system bordering on insanity. It is therefore of great advantage to engage in severer studies early in the day, and to devote the after part of the day and the evening to less intense application. It will be well to devote a portion of the evening, and especially the latter part of it, to light reading, music, or cheerful and amusing conversation. The excitement induced in the brain by previous study will be soothed by these influences, and will more readily subside, and sound and refreshing sleep will be much more likely to follow. This rule is of the utmost importance to those who are obliged to perform a great amount of mental labor. It is only by conforming to it, and devoting their mornings to study and their evenings to relaxation, that many of our most prolific writers have been enabled to preserve their health. By neglecting this rule, others of the fairest promise have been cut down in the midst of their usefulness.
Regularity is of great importance in the development and culture of the moral and intellectual powers, the tendency to resume the same mode of action at stated times being peculiarly the characteristic of the nervous system. It is this principle of our nature which promotes the formation of what are called habits. By repeating any kind of mental effort every day at the same hour, we at length find ourselves entering upon it, without premeditation, when the time approaches. In like manner, by arranging our studies in accordance with this law, and taking up each regularly in the same order, a natural aptitude is soon produced, which renders application more easy than it would be were we to take up the subjects as accident might dictate. The tendency to periodical and associated activity sometimes becomes so strong, that the faculties seem to go through their operations almost without conscious effort, while their facility of action becomes so much increased as ultimately to give unerring certainty where at first great difficulty was experienced. It is not so much the soul or abstract principle of mind which is thus changed, as the organic medium through which mind is destined to act in the present mode of being.
The necessity of judicious repetition in mental and moral education is, in fact, too little adverted to, because the principle on which it is effectual has not hitherto been generally understood. Practice is as necessary to induce facility of action in the organs of the mind as in those of motion. The idea or feeling must not only be communicated, but it must be represented and reproduced in different forms till all the faculties concerned in understanding it come to work efficiently together in the conception of it, and until a sufficient impression is made upon the organ of mind to enable the latter to retain it. Servants and others are frequently blamed for not doing a thing at regular intervals when they have been but once told to do so. We learn, however, from the organic laws, that it is presumptuous to expect the formation of a habit from a single act, and that we must reproduce the associated activity of the requisite faculties many times before the result will certainly follow, just as we must repeat the movement in dancing or skating many times before we become master of it.
We may understand a new subject by a single perusal, but we can fully master it only by dwelling upon it again and again. In order to make a durable impression on the mind, repetition is necessary. It follows, hence, that in learning a language or science, six successive months of application will be more effectual in fixing it indelibly in the mind, and making it a part of the mental furniture, than double or even treble the time if the lessons are interrupted by long intervals. The too common practice of beginning a study, and, after pursuing it a little time, leaving it to be completed at a later period, is unphilosophical and very injurious. The fatigue of study is thus doubled, and the success greatly diminished. Studies should not, as a general thing, be entered upon until the mind is sufficiently mature to understand them thoroughly, and, when begun, they should not be discontinued until they are completely mastered. By this means the mind becomes accustomed to sound and healthy action, which alone can qualify the student for eminent usefulness in after life. Much of the want of success in the various departments of industry, and many of the failures that are constantly occurring among business men, are justly attributable to the fits of attention and the irregular modes of study they became habituated to in their school-boy days. Hence the mischief of long vacations, and the evil of beginning studies before the age at which they may be understood. Parents and teachers should hence, at an early period, impress indelibly upon the minds of their children and pupils the ever true and practical sentiment, that what is worth doing at all is worth doing well. Although, at first, their progress may seem to be retarded thereby, still, in the end, it will contribute greatly to accelerate their real advancement, and in after life, whether employed in literary or business pursuits, will be a means of augmenting their happiness and increasing their prospect of success in whatever department of labor they may be engaged.
In physical education most persons seem well aware of the advantages of repetition. They know, for instance, that if practice in dancing, fencing, skating, and riding is persevered in for a sufficient length of time to give the muscles the requisite promptitude and harmony of action, the power will be ever afterward retained, although rarely called into use. But if we stop short of this point, we may reiterate practice by fits and starts without any proportional advancement. The same principle is equally applicable to the moral and intellectual powers which operate by means of material organs.
The impossibility of successfully playing the hypocrite for any considerable length of time, and the necessity of being in private what we wish to appear in public, spring from the same rule. If we wish to be ourselves polite, just, kind, and sociable, or to induce others to become so, we must act habitually under the influence of the corresponding sentiments, in the domestic circle, in the school-room, and in every-day life, as well as in the company of strangers and on great occasions. It is the private and daily practice of individuals that gives ready activity to the sentiments and marks the real character. If parents or teachers indulge habitually in vulgarities of speech and behavior in the family or in the school, and put on politeness occasionally for the reception and entertainment of strangers, their true character will shine through the mask which is intended to conceal it. The habitual association to which the organs and faculties have been accustomed can not thus be controlled. Parents hence, in addition to correct personal influence in the family, should provide for their children teachers whose habits and character are in all respects what they are willing their children should form. If they neglect to do this, the utmost they can reasonably expect is that their children will become what the teacher is.
The principle that repetition is necessary in order to make a durable impression on the organ of the mind, and thus constitute a mental habit, explains how natural endowments are modified by external situation. The extent to which this modification may be carried, and is actually carried in every community, is much greater than most persons are aware of. Take a child, for example, of average propensities, sentiments, and intellect, and place him among a class of people in whom the selfish faculties are exclusively exercised—a class who regard gain as the end of life, and look upon cunning and cheating as legitimate means, and who never express disapprobation or moral indignation against either crime or selfishness—and his lower faculties, being exclusively exercised, will increase in strength, while the higher ones, remaining unemployed, will become enfeebled. A child thus situated will, consequently, not only act as those around him do, but insensibly grow up resembling them in disposition and character; for, by the law of repetition, the organs of the selfish qualities will have acquired proportionally greater aptitude and vigor, just as do the muscles of the fencer or dancer. But suppose the same individual placed, from infancy, in the society of a superiorly endowed moral and intellectual people, the moral faculties will then be habitually excited, and their organs invigorated by repetition, till a greater aptitude will be induced in them, or, in other words, till a higher moral character will be formed. The natural endowments of individuals set limits to these modifications of character; but where original dispositions and tendencies are not strongly marked, the range is very wide.
In the cultivation of the brain and mental faculties, each organ should be exercised directly upon its own appropriate objects, and not merely roused or addressed through the medium of another organ. When we wish to teach the graceful and rapid evolutions of fencing, we do not content ourselves with merely giving directions, but our chief attention is employed in making the muscles themselves go through the evolutions, till, by frequent repetition and correction, they acquire the requisite quickness and precision of action. So, when we wish to teach music, we do not merely address the understanding and explain the qualities of sounds. We train the ear to an attentive discrimination of these sounds, and the hand or the vocal organs, as the case may be, to the reproduction of the motions which call them into existence. We follow this plan, because the laws of organization require the direct practice of the organs concerned, and we feel instinctively that we can succeed only by obeying these laws. The purely mental faculties are connected during life with material organs, and are hence subjected to precisely the same laws. If, therefore, we wish to improve these faculties—the reasoning powers, for example—we must exercise them regularly in tracing the cause and relations of things. In like manner, if our aim is the development of the sentiments of attachment, benevolence, justice, or respect, we must exercise each of them directly and for its own sake, otherwise neither it nor its organ will ever acquire promptitude or strength.