Soon, by an unavoidable fatality, the disorder that had affected the body recoils upon the mind; for the Author of nature has ordain’d that most of the operations of the latter should stand in need of the assistance of the former; which has given occasion to the following just observation of Pliny the younger[11], and long before him it was observed by Democritus, that the mind is supported by what supports the body. “Augescit mens cum adest sanitas, adeoque huic ut prospiciant, qui recte sentiant consentaneum est: ubi vero corporis habitus dolet nec mens ad virtutis meditationem est alacris.” “The mind acquires new vigour whilst the body is in health; therefore all those who think justly will take care of the latter: but, when the body is in a painful state, the mind is less alert in the meditation of virtue[12].” Should it then seem surprising, if, when the tenor of the brain and nerves is broken by the efforts of the mind, the latter should decline in its turn? First of all it is depriv’d of its fortitude; distrust, terror, and melancholy, seize upon it; and he who would have stood undaunted amidst a falling world a few months before, is every moment fill’d with terror and consternation, as soon as his nerves are affected by a hypochondriac disorder. Relentless tyrants may have condemn’d to death philosophers whom they hated; but it never was in their power to subject them to the dread of death, which they had long shaken off. O how much more cruel would they have been, if they had granted them their lives, and had it in their power to torment their minds with hypochondriacal terrors!
Thus render’d unequal to the task of study, the learned are at last under a necessity of quitting their belov’d pursuits; for, as the strength of their nerves diminishes, their attention fails, the memory begins to lose its tenaciousness, the ideas are obscur’d, and an uneasy sensation of heat over the whole head, a dreadful palpitation, the most extraordinary weakness, and a groundless fear of approaching death, oblige them to discontinue their application. Their strength being at last repair’d by rest, nourishing aliments, and exercise, they renew their assiduity in study, but are soon oblig’d to quit their books as before. Thus the whole day is lost; and when evening approaches and they retire to bed, their weakness and anxiety make them pass their nights most dismally, whilst the great mobility of their nerves prevents their sleeping, and sometimes increases to such a degree as totally to deprive them of the power of thinking. I know a young man, upon whom an intense application to study had this extraordinary effect, that, if he read even a few pages, he was torn with convulsions of the muscles of the head and face, which assum’d the appearance of ropes stretch’d very tight.
Nor does too intense an application produce only slight and transient convulsions of the muscles; it likewise renews and generates the most dreadful nervous disorders. Galen[13] mentions a grammarian, who was seized with a fit of the epilepsy, whenever he meditated profoundly, or taught with vehemence. I myself have seen instances of it. And the illustrious Van Swieten laments the case of youths of the brightest hopes, who have been seiz’d with a dreadful and incurable epilepsy, upon being compell’d by severe masters to apply to their studies with scarce any intervals of relaxation. Hoffman[14] makes mention of a young man, who, as often as he weary’d out his memory and his genius by attentive study, was seiz’d with a momentary epilepsy, a palpitation of the heart, and a trance; but when he remitted of his assiduity, was always tolerably well. This the celebrated Petrarch likewise unhappily experienc’d, being seiz’d with an epilepsy through his great application to study, to which he was immoderately attach’d. In a public promotion, one of the candidates for literary honour, after having pursu’d his studies with the moil arduous application both day and night, through a too great attention to his oration, that he might be able to say it accurately by heart, was suddenly seiz’d with a catalepsy and fell down[15].
The labour of the mind not only produces nervous disorders, but, by means of the nerves, gives rise to other complaints. An eminent mathematician, who was troubled with an hereditary gout, and had always liv’d soberly and chastely, hasten’d a paroxysm by applying a long time to the solution of a difficult problem[16]. And the case of the chevalier de Pernay is very extraordinary. After four months of the closest study imaginable, and without any previous disorder, his beard fell first, then his eye-lashes, then his eye-brows, then the hair of his head, and finally all the hairs of his body[17]. Did this proceed from the great relaxation of the roots, from which the hairs grow; or from the want of nutrition? Certain it is, that an intense application of mind relaxes the whole corporeal frame, and prevents all nutrition for two reasons; for this is the effect of thought, not upon all, but upon most constitutions, that it accelerates the pulse, and produces a fever, which, by dissolving the nourishing jelly of the fluids, occasions paleness, leanness, consumption, and a sort of wasting of the nerves; on the other hand, the cessation of the action of the nerves, is capable of producing it. Nor does it less cease in the whole body, whilst it is obstructed by application of mind, than when it is stopped by a swelling or a ligature in any part. We should not be too inquisitive in prying into causes; and many circumstances relating to nervous disorders will for ever remain unknown: but if any one should be curious to know how the too great tension of the nerves is hurtful, I will briefly give him my sense of the matter. The body is exhausted by too great an evacuation; hence arises weakness, an extraordinary tenuity of the humours, and, what it is generally productive of, a diseased mobility. Suppose the blood were to run copiously from a wound, or the gastric fluids were to be pour’d forth by the anus, or the breasts suck’d too long, or a greater discharge of saliva made by spitting, or the wretched body were to be troubled with a long diabetes, or in short, any other evacuations were too much increased, the strength would decline, and the health be lost; but whilst the nerves act, their fluid runs out of the body, and carries off the strength with it; nor is there any thing in the body either more labour’d, more necessary in many animal functions, or more intimately connected with strength. In studious men, therefore, a perpetual dissipation of the nervous fluid springs from the incessant action of the nerves, attended with weakness, and an extraordinary mobility, from whence all the above-mention’d diseases easily take rise; these are very dreadful, but diseases still more dreadful remain to be describ’d.
It is not easy for the mind not to throw out at will such motions as it has powerfully conceiv’d; and this is a second cause of the diseases of studious men, from whence spring so many errors and wanderings of the mind, to be chang’d for death only, so many phrenzies and deliriums: for whilst ideas no longer answer to their external objects, but to the internal disposition of the brain, the latter being agitated by its own motion, either entirely, or in part, is unable to receive new vibrations, to be transmitted, all, or some, by the senses; whereas those that are spontaneous cannot be check’d.
The brain of Blaise Paschal was so vitiated by passing his life in the laborious exercises of study, thought, and imagination, that certain fibres, agitated by incessant motion, made him perpetually feel a sensation, which seem’d to be excited by a globe of fire being plac’d on one side of him; and his reason being overpower’d by the disorder of his nerves, he could scarce banish the idea of the fiery globe being actually present. Spinello painted the devils thrown from Heaven by the Almighty, and gave so fierce a countenance to Lucifer, that he was struck with horror himself; and during the remainder of his life, his imagination was continually haunted with the figure of that demon, upbraiding him with having made so shocking a portrait of him. There are many others, whom the force of genius too much rous’d, has for ever hurried beyond the boundaries of truth. Gaspar Barlæus, who was at once an orator, a poet, and a physician, was not ignorant of this danger, concerning which he admonish’d his friend Constantius Huygens[18]; but being blind with regard to himself, he by immoderate studies so broke the force of his sensorium, that he thought his body was made of butter, and carefully shun’d the fire, lest it should melt him, till being at last tir’d of his excruciating fears, he leapt into a well. I must still grieve for a friend of a penetrating genius, an excellent understanding, of strict morals, and one that seem’d born for a better fate; who being animated with too great a love of learning, and in particular of the medical science, by reading night and day, observing, making experiments, and meditating, at first became sleepless; then began to talk, sometimes incoherently, and sometimes rationally; at last run mad, and having scarcely escap’d with life, never recover’d his reason. I have known many others, who by study alone were first rendered phrantic, or crazy, and at length became idiots. I love, esteem, and honour an illustrious man, and a man of extraordinary abilities, who being twelve hours intent upon settling a difficult memorial, after having finish’d his work, became delirious till a soft sleep quieted the state of his nerves. Observers give us accounts of many similar cases, and I was inform’d by a witness who may be confided in, that Peter Jurieu was formerly famous for his talent at disputing, by his labours in writing books of controversy, and expounding the apocalypse, so disorder’d his brain, that though he thought like a man of sense in other respects, he was firmly persuaded that the seven fits of the cholic, with which he was tormented, had been occasion’d by a constant fight between seven horsemen that were shut up in his bowels. There have been many instances of persons, who thought themselves metamorphos’d into lanterns, and who complain’d of having lost their thighs.
But those are affected in the most dangerous manner, who dwell too long upon one and the same thought; for thus one part of the sensorium being longer stretch’d than the rest, without being ever reliev’d by the others in their turn, is the sooner broke; for as the body suffers more if one or but a few muscles alone act, so the brain is the less fatigued when various parts act successively; the part which discontinues recovers its strength, whilst the others are at work; and that is durable which does not want alternate rest.