Many years ago I knew a woman, who appear’d to have very good sense for five and twenty years; but having, unhappily for her, embrac’d the sect of the Herrenhutters, she became entirely inflam’d by the love of our blessed Saviour, and of him alone; and she dwelling entirely upon this idea both day and night, it so broke the tone of her brain, that in a few months time she became an idiot; but still she was so mindful of her Lamb, that visiting her every day for half a year together, and frequently addressing my discourse to her, I could never hear any other words from her than my sweet Lamb; and this she utter’d every half hour, with downcast eyes, and was the only word she spoke for a year and a half; which time being elapsed, she pin’d away and died. And to pass by other examples, there was not long ago in this academy, a young man of bright hopes, who being too earnestly solicitous about squaring the circle, died mad in the Paris hospital.
The third cause of the disorders of the brain, is, that law to which the human machine is subjected; that a new quantity of blood should be added to the part that acts. The illustrious Morgagni knew a man of learning at Boulogne, who whenever he gave his mind to abstract meditations in the morning, before he rose, was sure to bleed at the nose for a short time after[19]. Therefore as often as the brain increases its action, it is moisten’d with an additional quantity of blood, which, giving a new tension and a quicker motion to the vessels, brings on both the sense of pain and heat already mentioned, and many more grievous symptoms; namely, according to the different state of the brain, of the blood, and external objects, it occasions dilatations of the veins and arteries, obstructions of the nerves, inflammations, suppurations, scirrhous tumours, ulcers, dropsies, and thence head-achs, deliriums, drowsiness, convulsions, lethargy, apoplexy, and continual obstinate watchings, which cruelly torment the studious, and afflict them with new diseases; for what diseases, what perturbations of the mind do not protracted watchings give rise to? The great Boerhaave was six weeks without sleep, after profound study and meditation; and at the same time so indifferent to every thing, that scarce any object whatever affected him[20]. And which of you, learned auditors, has not found by experience, that a slight and disturb’d sleep, a sleep that scarce gives refreshment, generally follows a day pass’d in study. A slight irritation of the brain causes want of sleep; from one more considerable arise convulsions and drowsiness; from the greatest of all a mortal apoplexy, which disorder often puts an end to the lives of learned men. The reason is, that that part suffers which was guilty of the excess, and whilst the strength of the brain is relax’d by study, and fresh blood is forc’d into it, it must sooner or later be quite overwhelm’d, especially at the time that some new cause adds force to the blood that impells it; thence it has frequently come to pass, that learned divines in preaching, and learned professors in delivering their lectures, or disputing, as was the case with the celebrated Curtius at Leipsick, expir’d on their very chairs; and Livy the historian has preserv’d to us the history of king Attalus, who died in the assembly at Thebes, whilst he was animating the Bœotians by an harangue to enter into an alliance with the Romans.
I saw a reverend pastor, who on Whitsun-sunday, after having preach’d long and with vehemence, whilst he was distributing the host to the people, was first seiz’d with trembling, then stammer’d, then was delirious, then fell down in an apoplectic fit, and continuing delirious ever after, though in an advanc’d age, liv’d for some months in a state of infancy. The celebrated Morgagni likewise mentions a preaching monk, who was seiz’d with a violent apoplexy before his congregation, and quickly died; his vehemence of delivery conspiring with a plethora to destroy him[21]. A professor at Berne, deeply versed in the oriental languages, a man in the prime of life, but of indefatigable industry, not long since sunk into a second infancy, and a state of idiotism, his brain being overflow’d by water, which stagnated in it[22].
We must not forget, in enumerating the injuries suffered by the brain from this overflowing of the blood, that the disorder of the nerves which causes the hypochondriac disposition, is increased; their little tubes being dilated are constantly weaken’d, grow soft, and make less resistance to impressions, which is one of the chief causes of the hypochondriac disorder.
Nor do the sufferings of studious men end here, since from another law, which holds equally in the animal œconomy, a fourth cause of the disorders of the learned springs from an over violent labour of the mind; for the animal fibre is indurated by being used, the whole machine grows callous as it grows old; the parts that are exercised by labour become hardened in workmen; the brain of studious men contracts a callosity, so that becoming unequal to the task of forming ideas, they fall into a premature dotage: thus the too great softness of an infant’s brain, and the too great hardness of a brain occasioned by study, are equally ill adapted to produce those vibrations, without which the force of thought is lost. Let the fibre be moisten’d with water, or stiffened with lime and sand, it in both cases becomes equally incapable of performing its function. At first the memory is impair’d, as Galen justly observes, and then reason itself is disturb’d[23].
Nor is there any necessity that the mind should meditate great and sublime objects, to impair the strength of the nervous system; a too protracted use of the eyes has often given rise to innumerable nervous disorders; concerning which, the testimony of Gunzius is of the utmost authority[24]. And every weak man must know by experience, how much too great a use of the eyes weakens the head. Of this I have already given an example, and have often found it by experience; for when I contemplate any object a considerable time, after the fit of a fever, or any other disorder, and before my health is quite recovered, I am seiz’d with a vertigo, a sickness in the stomach, and a disagreeable listlessness of the whole body.
In order to vindicate literature from the charge brought against it, you will doubtless object, that many men of profound learning, have liv’d to the most advanc’d age, and retain’d their powers both of mind and body unimpair’d to the last. I have heard of many, I have myself seen more; nor can either you or I ever forget that truly illustrious man, that man of universal learning, who as he was worthy of it, enjoy’d general love and veneration; who was the ornament, honour, and delight of this academy for above fifty years, and whom we all with equal wonder and satisfaction saw enter upon his 90th year, without either his reason, or his senses being in the least impair’d. But all are not equally happy, and there are few men endued with such strength, both of mind and body, as to undergo such labours with impunity, if even those can be said to undergo them with impunity, who attain to that stage of life, which they perhaps would have greatly exceeded, had they liv’d in a different manner. Some men are by nature insatiable in drinking wine, others are born cormorants of books, and never glutted with the acquisition of learning: nor should it be pass’d over in silence, that almost all the learned men, who are look’d upon as its masters by the human species, all liv’d to a great age; as Homer, Democritus, Parmenides, Hippocrates, Plato, Plutarch, Lord Bacon, Galilæo, Harvey, Wallis, Boyle, Locke, Leibnitz, Newton, Boerhaave. Can it then justly be inferred, that violent exercises of the mind are not hurtful? Take care how you draw so false a conclusion? But, as I said awhile ago, some men are born with happy constitutions for meditation, and perhaps that excellent constitution of the fibres, productive of longevity, is the same that produces great geniuses;
Mens sana in corpore sano,
A sound mind in a healthy body;