Retirement from all human society is likewise hurtful to them; for man, whom nature made for man, she intended also should be benefited by society.
But nothing renders study and application more pernicious than the sadness that accompanies them: study is capable of clouding the temper of the happiest man with melancholy: if real and external causes of grief are added to this, the mind, overwhelm’d with so many strokes, at last sinks under them, and in its own ruin involves that of the body. Anxious cares are likewise hurtful; so that I can hardly conceive how great men, whom the difficulty of their undertakings kept in unremitting meditation, and whom the uncertainty of events fill’d with continual anxiety, could go through with such great undertakings. Nature endow’d Cæsar, Mahomet, Cromwell, Paoli, and some few more, with faculties which she refused other mortals, and which, notwithstanding, would scarce have enabled them to perform such great exploits without the assistance of sobriety and incessant action.
We should not, however, imagine, that the learned alone destroy their health by mental labour; it is of no consequence what the object is that engages the mind, if it applies a considerable time and with earnestness, it wastes both its own strength and that of the body. Kings, senators, ministers, ambassadors, and all those concern’d in the administration of public affairs, are subject to the same unhappy fate which the learned deplore, if they labour with equal assiduity in transacting public affairs, as the learned in perusing books. But it is their happiness, that, in the various business and dissipation of their places, they are oblig’d often to quit their closets, and even against their wills are, by a salutary necessity, compell’d to take frequent exercise: the chief use of this is, that it admirably prepares the blood for the generation of fresh animal spirits, and in the same time it brings a greater quantity of blood to the secerning organs, and so restores what thought had exhausted, and frames new instruments for the thinking mind. But nothing can force the studious from their books, and they are quite enervated by inaction: to palliate which you will perhaps bring some examples of men who have liv’d to a great age, though they used but little or no action. There are but few men; but you will, I doubt not, bring many women. Take notice, however, that, though they had not much muscular motion, they had many other helps, by which nature promotes the circulation of the blood, viz. an agreeable stirring of the passions, which excites, and does not destroy; a constant chearfulness and eternal loquacity, and other assistances of a similar nature: they likewise use but little food. The case is quite different with the learned: they do not live with the same sobriety; and therefore it is no wonder that they enjoy their health worse than any other class of men.
Thus have I laid before you the chief causes, from which the diseases incident to the studious take rise; and I should never make an end, were I to enumerate the inferior causes, which professors have a bad custom of assigning from their own invention: I shall therefore pass by all the secondary causes. But there are men, truly learned, illustrious votaries of the muses, who, besides the disorders that spring from too assiduous an application of mind, experience others, owing to the nature of the object that engages them. Anatomists often contract malignant fevers by breathing putrid air, and other diseases from the corruption of the bile, from the matter in which their hands are constantly immersed, a slight excoriation arising, or an inconsiderable wound, which sometimes end in their deaths. Chemical experiments are attended with danger, and an acid smoke, of a very penetrating nature, would have kill’d the great Boerhaave, if there had not been at hand an alcaline spirit, which overcame the acid and expanded the compressed lungs. Botanists have been often hurt by the plants for which they have so strong a passion. These, and the like, rather relate to the disorders of artificers, (excuse the expression); but this discourse turns upon the disorders which study brings upon some of the organs.
The first that offer are the eyes, which constant attention so fatigues, that I have often seen doctors who had not attain’d to their thirtieth year, and yet could hardly bear the light, especially candle-light; and were scarce able to read a few pages without their eyes being suffused with tears, then growing dim, and at last quite incapable to distinguish any object. But the eyes are much sooner and much more easily affected by reading at night; for there is not a man living who has not experienc’d, at least once in his life, how much they suffer by the motion of light and the irritation of smoke.
Orators have disorders peculiar to themselves, which are of a very grievous nature: for however reading aloud may be of service to the lungs, vehement declamation is hurtful: and how often do preachers or lawyers pass whole days and nights in their studies, when the lungs, unequal to the efforts of speaking, are severely injur’d. How much more happy are those pastors of the church, who cultivate learning, but are kept from their studies by other avocations, being in this respect equally privileg’d with the physicians, whom the health of their fellow-creatures does not suffer to impair their own health by study. Happy likewise are all those whom the nature of their business calls off from study; for though they are not thereby exempted from the labours of the mind, the change of their employments is however a great consolation to them. But unhappy are those preachers, who, being exempt from other ecclesiastical functions, live only to study, and compose eloquent discourses; unhappy those lawyers, who are entirely taken up with managing and pleading causes; for their health is insensibly impaired by the life they lead, their throat, wind-pipe, and lungs, are irritated, heated, and inflamed; hence proceed catarrhs, hoarseness, a broken voice, spitting of blood, a cough, a fever, great weakness, and at last a consumption; and, whilst they give light to others, they are extinguished like the snuff of a candle, unless they take care of themselves. This is what Cicero did, who, being told that he was beginning to be consumptive, avoided pleading for two years, by the advice of his physicians; in which time he recovered his strength and health, which had been greatly impaired[35].
These, worthy auditors, are most of the disorders that are occasioned by too great an attachment to study, or a continued application of the mind to any object whatever: nor are we to imagine that all undergo the same sufferings; much variety is here occasioned by the various constitutions of men, by their different ages, and the diversity of their external circumstances. There are few or no bodies but what have some weak parts, which suffer the first attacks of every disorder. He whose stomach is naturally weak, or who has rendered it so by living in a manner not suited to his constitution, will first complain of pains in the ventricle, whilst the nerves, which he received strong in a weak body, are still in a good state. On the other hand, he who is troubled with weak nerves, but has a good stomach, will long suffer all sorts of nervous disorders, the digestion remaining unhurt.
He in whom the muscular or cellular fibres are relaxed, will complain of lassitude, drowsiness, weakness, swellings, his head and stomach remaining unhurt. Another will suffer all the disorders incident to the lungs, who received them from nature not indued with a proper degree of strength. In these the vascular system of the head is weak, they are troubled with incessant head-achs, or bleeding at the nose, to which other studious youths are obnoxious, their intense application to study forcing the blood upwards. Finally, every man, according to the part affected with weakness, is liable to complain of some disorders more than others.