There are two principal sources, from whence all the sufferings of the studious flow; the constant exercise and application of the mind, and the continual rest of the body; for they are as indolent in body, as they are busy and active in mind. By enumerating the ills, that arise from both causes, a dreadful crop of diseases will be display’d.
Let metaphysicians bewilder themselves in inquiries, how the mind governs the body, and is govern’d by the latter in its turn; physicians, descending to considerations of less importance, but of greater certainty, perhaps, and little sollicitous about the causes of this mutual government, and but confining their inquiries to phænomena, know by experience, that certain emotions of the mind necessarily arise from certain conditions of the body, and that by particular emotions in the mind particular changes are unavoidably produc’d in the body, and that whilst the mind thinks, some part of the brain is stretch’d. We make no other inquiry; it would be of no use to know any thing farther.
So close is the connexion between mind and body, that we cannot well conceive the operations of the one independent of some correspondence with the other. For as the senses are incapable of conveying the materials of thought to the soul, without the motion both of their own fibres and those of the brain, so, whilst the mind revolves these cogitations, the organs of the brain are more or less stimulated to act, stretch’d, and have oscillatory motions excited in them. The mind agitates the machine; and these are the labours of the medullary part, which, being so tender, does not suffer the less by these motions; and every man easily feels that in himself, which the strongest arms experience after the most violent exercise.
For which of you, that has been addicted to a studious life, has not often found, after intense thought, that the innermost part of the brain has been affected by a troublesome heat, and intense pain, such as the muscles feel when fatigu’d with long labour? Nor does the medullary part of the brain suffer alone, but the very eyes themselves can perceive the force of the thinking soul, extended beyond the brain: for whilst we look upon a man that meditates seriously, all the muscles of his face appear stretched, nay sometimes convuls’d. Nor does the brain, the medulla of which is the source of the nerves, suffer alone, but they themselves are hurt; and Plato has admirably shewn, in the masculine style in which he so greatly excell’d, how much the exercise of the mind prejudices the body. “Quando anima, inquit, corpore admodum potentior est, exultatque in eo atque effertur, totum ipsum intrinsecus quatiens languoribus implet. Quando etiam ad dicendum, investigandumque, collectis in unum viribus, vehementer incumbit, liquefacit prorsus corpus, & labefactat; denique cum ad dicendum, differendumque privatim & publice ambitiosa quadam concertatione contendit, inflammat corpus atque resolvit. Tam arcta enim lege consortii, sic Ramazzini, fœderantur anima & corpus ut omnia tam bona quam mala unius in alterum vicissim corrivent, ac veluti, ex corporis nimia exercitatione, anima ad mentis functiones languescit, ac torpet, sic ob nimiam animæ contentionem, circa sapientiæ studium, corpus marcescat necesse est, absumptis nempe spiritibus, communi scilicet instrumento ad materiales & spirituales operationes rite obeundas.” “As the mind, says he, is far more powerful than the body, and exults and is elate therein, it affects it inwardly, and fills it entirely with languor; and when, by gathering together its strength, it applies earnestly to learning and to the investigating of things, it quite dissolves and unhinges the body: finally, when with an ambitious emulation it exerts itself to speak and harangue both in private and public, it inflames the body and relaxes it. For, as Ramazzini observes, the soul and body are united by so firm a league, that all the advantages and disadvantages of the one must affect the other; and as the soul is rendered languid in the mental functions, and become stupified in the same manner by the too great application of the mind to the study of wisdom, the body must unavoidably pine away, the animal spirits being consum’d, which are the only instruments of rightly performing both material and spiritual operations[2].” These are indeed observations highly just. For he who is not ignorant what a multitude of nerves there are in the animal system, who is sensible that there is no function that can be performed without them, will easily apprehend that by the fatigue of the medulla a languor may be brought upon all the nerves, so that the several functions may be weakened, and the strength of the body may, without its being exercised, be totally exhausted.
It is universally known that there are books compos’d without any strength of genius, which appear quite insipid and unaffecting to the reader, and only tire the eyes; but those that are compos’d with an exquisite force of ideas, and with an exact connexion of thought, elevate the soul, and fatigue it with the very pleasure, which, the more compleat, lasting, and frequent it is, breaks the man the more[3].
Malebranche was seized with dreadful palpitations in reading Descartes’s Man; and there is still living at Paris a professor of rhetoric, who fainted away whilst he was perusing some of the sublime passages of Homer[4].
The head itself, and the nerves, and the stomach which is fuller of nerves than any other part, first suffer for the errors of the mind.
An eminent person, who had impair’d his health by too intense an application to study, was immediately seiz’d by a terrible vertigo, if he happen’d to listen attentively to a person telling a story. He likewise complained, that nothing could give him greater uneasiness than his attempting to recall the memory of any thing, for then he was put to the greatest pain imaginable, and sometimes seiz’d with a fainting fit, attended with a sense of extreme lassitude. Nor could he desist from his effort after he had once begun it, though he labour’d ever so much for that purpose; but was under a necessity of proceeding as he had begun, till he fainted away[5]. The illustrious Viridet, formerly my fellow-citizen, knew a woman who, whenever she us’d any application of mind, was seiz’d with a severe fit of the colic[6]. And a late author speaks of a man who never either thought intensely, or experienc’d any lively sensation, or was put in a passion, but his whole arm immediately swell’d up[7]. Both of which cases may be explained by the defect of the nerves alone, and the action of the mind upon the nerves.
Daily observation proves the force of the mind’s action upon the stomach; and this every man has an opportunity of experiencing in himself; for the more intensely any man thinks, and the more strongly he exerts the reflecting powers of his mind, the more slowly and with the greater difficulty, cæteris paribus, does he digest what he eats; and, on the other hand, the freer a man’s mind is from reflexion, the more readily and the better he digests. It is observable that fools always eat and drink a great deal, and yet digest perfectly well, even though they lead a sedentary life, and do not surpass others either in the bulk or strength of their bodies: whilst men of genius and abilities, though they have strong muscles, and take exercise sufficient, are obnoxious to crudities in the stomach and slowness of concoction [8]. Boerhaave, who resided a long time in a city renown’d for learning, has observ’d that studies excite a disagreeable sensation at the upper orifice of the stomach; and that, if this be neglected by the studious, madness ensues[9]. My illustrious friend Pome knew a man of learning, who had made his stomach so infirm by intense application, that immediately after eating he vomited[10]. I myself have seen some, who, when their minds were wearied out with constant study, being taken ill, at first lost all appetite, then were seiz’d with a weakness of their whole bodies, and at last with dreadful paroxysms, which began with vomiting, and ended in convulsions and a total privation of their senses.