1. First we are to consider the circumstances of the body which have an effect upon the mental se quences. The object is, to ascertain which have a tendency to introduce those sequences which are fa vourable, which to introduce those that are unfavour able, to human happiness, and how to turn this know ledge to account.
Health and sickness, or the states of body which those names most peculiarly express, are the first of the circumstances which we have enumerated under this head. That these states have a tendency to in troduce very different trains of thought is matter of vulgar experience; but very little has been done to examine such trains, and to ascertain what in each is favourable, and what is unfavourable to human hap piness.
We have already seen, that the trains which are favourable to Intelligence, Temperance, Generosity, and Justice, are the trains favourable to human hap piness. Now, with respect to Intelligence, it will be seen, that Health is partly favourable, and partly un favourable; and the same is the case with sickness. Health is favourable, by allowing that time to be given to study, which many kinds of sickness with• draws; by admitting a more vigorous attention, which the pain and languor of sickness often divide. It is unfavourable, by introducing that flow of plea surable ideas, which is called high spirits, in a de gree unfavourable to the application of attention; and by leadingto that passionate pursuit of pleasure, which diminishes, if it does not destroy, the time for study. The mode in which disease operates upon the mental sequences is a subject of great complexi ty, and in which little has yet been done to mark distinctly the events, and ascertain the order of their succession. Cabanis, in his seventh memoir, entit led, De thafiumce des Maladies sur la Formation des Ides et des Affections Morales, has made a use ful beginning toward the elucidation of this subject ; but here, as elsewhere, he is too often general and vague. Instruction may also be gleaned from Dar.
win; but the facts which bear upon this point ra ther drop from him incidentally, than are anywhere put together systematically for its elucidation. As they were both physicians, however, of great expe rience, and of unusual skill in the observation of mental phenomena, their opinions are entitled to the greatestThe result of the matter is, that an improved is no trifling branch of the art and science of education. Cabanis, accordingly, con cludes his memoir with the two following proposi tions: lmo, L'etat de maladie influe dune maniere directe sur Is formation des ideas et des affections morales: nous avons meme pu montrer dana quel-. ques observations particulieres, comment cette influ ence s'exerce.
" 2do, L'observation et l'experience nous ayant fait decouvrir lea moyens de combattre assez souvent avec succes l'etat de maladie, l'art qui met en usage ces moyens, peat done modifier et perfectionner les operations de l'intelligence et les habitudes de la vo lontk." As it is chiefly through the nervous system, and the centre of that system, the brain, that the men tal sequences are affected, and as all the sensitive parts have not an action equally strong, nor equally direct, upon the nerves and brain, diseases 'affect the mental sequences differently, according to the parts which they invade. The system of the nerves and brain is itself subject to different states of disease. Classified, with regard to the functions which that system performs, as the organ of sensibility and of action, these states are thus described by M. Caba nis : " 1. Excess of sensibility to all impressions on the one part; excessive action on the organs of motion on the other. Q. Unfitness to receive impressions, in sufficient number, or with the due degree of ener gy ; and a diminution of the activity necessary for the production of the motions. S. A general dis turbance of the functions of the system, without any remarkable appearance of either excess or defect. 4. A bad distribution of the cerebral virtue, either when it exerts itself, nnequally in regard to time, ha.. ving fits of extraordinary activity, followed by others of considerable remission; • or when it is supplied in wrong proportion to the different organs, of which some are to a greet degree abandoned, while there appears in others is concentration of sensibility, and of the excitations or powers by which the movements are affected." The effects upon the mental sequences are repre sented in the following general sketch, which has the advantage of being tolerably comprehensive, though it is unhappily both vague and confused: "We may lay it down as a general fact, that, in all the marked affections of the nerves, irregularities, less or great er, take place, relative both to the mode in which impressions are received, and to the mode in which the determinations, automatic or voluntary, are form ed. On one part, the sensations vary incessantly and rapidly with respect to their vivacity, their ener gy, and even their number; on another, the strength, the readiness, the facility of action exhibit the great est inequalities. Hence perpetual fluctuation, from
great excitement to languor, from elevation to de jection ; a temper and passions variable in the high est degree. In this condition, the mind is always easily pushed to extremes. Either the man has ma ny ideas, with great mental activity and acuteness ; or he is, on the contrary, almost incapable of think ing. It has been well observed, that hypochondria.. cal persons are by turns both courageous and coward.. ly ; and as the impressions are habitually faulty ei ther by excess or defect, in regard to almost all ob jects, it is seldom that the images correspond to the reality of things ; that the desires and the will ob tain the proper force and direction. If, at the same time with these irregularities, which arise from the nervous system, should be found a weakness of the muscular organs, or of some important viscus, as, for example, of the stomach,—the phenomena, though still analagous in the main, will be distinguished by remarkable peculiarities. During the interval of languor, the debility of the muscles will render the sense of weakness, the fainting and drooping, still more complete and oppressive; life will appear ready to escape at every instant. The passions are gloomy, excited by trifles, selfish ; the ideas are petty, nar row, and bear only upon the objects of the slightest sensations. At the times of excitation, which arrive the more suddenly, the greater the weakness; the muscular determinations do not obey the impulses of the brain, unless by starts, which have neither energy nor duration. These impulses serve only to convince the patient more profoundly of his real imbecility; they give him only a feeling of impatience, of dis content, and anxiety. Desires, often sufficiently keen, but commonly repressed by the habitual feel ing of weakness, still more increase the discoura ging impression. As the peculiar organ of thought cannot act without the concurrence of several others, and as, at that moment, it partakes in some degree of the weakness which affects the organs of move ment,, the ideas present themselves in crowds; they spring up, but do not arrange, themselves in order; the necessary attention is not enjoyed ; the conse quence is, that this activity of the imagination, which we might expect to afford some compensation for the absence of other faculties, becomes a new source of dejection and despair." In this passage, the mental sequences which peed. cular states of disease introduce are clearly shown to have a prodigious influence upon human happiness; but the effects which are produced in respect to intelligence, temperance, generosity, and jus tice, are mixed up together; and the author rather shows how much this subject deserves to be studied, than gives us information from which any consider able degree of practical utility can be derived. The connection between particular states of body, and particular mental trains, must be carefully watched and recorded. When the events, one by one, are accurately distinguished, and made easy to be re cognised, and when the order in which they follow one another is known, our power over the trains of those events; power to prevent such as are unfavour able, to produce such as are favourable, to human happiness, will then be at its height ;Ind how to take care of his heads will be one of the tearing pasts of the moral and iotellectral education of The state of the body, with regard to health and disease, is the inherent circumstance of the greatest importance, and we mart pass over the rest with a cursory notice The next we mentioned, ire, strength and weakness, meaning chiefly unseal: strength and weakness; and the nitural, habitual, not the acci dental, or diseased, state. It is a common mouagh ob servation, that moscalar strength is apt to dinivr the owner from wand pursuits, and engage him in such as are more of the aniad kind ; the aapthition said &splay of physical powers. Few men of great bodily powers have been mesh rfistinguished for men tal escellessee ; some of the _Itmt ornaments of henna nature have been for bodily weak ness. Muscular strength is liable to operate unfa vourably the moral, as well as the intellectual trains of It diminishes that respect for other men, which is so necessary to resist the im pulses of passion ; it presents innumerable occasions for playing the tyrant with pay ; and fosters, therefore, all that rain of ideas, in wbicla the tyran nical vices are engendered. Cabsnis remarks, and the fact is worthy of the greatest attention :—" Presque tons let grand' sciksats sont des becomes dune structure orprique vigooreuse, remarquables par la fermete et Is tenaciti de !curs fibres muscuLsires." It is evident, therefore, bow deeply it concerns the happiness of mankind, that the mental trains which this circumstance has a tendency to raise, should be accurately known, as thus alone the means can be known, bow that which is hurtful an be avoided, that which is useful be introduced.