It was dangerous to be a man of letters in the eighteenth century. All that rumination; such single-minded concentration; countless hours hunched over the escritoire. “Some men are by nature insatiable in drinking wine, others are born cormorants of books”, wrote the Swiss physician Samuel-Auguste Tissot in An Essay on Diseases Incidental to Literary and Sedentary Persons (1768). As with the reckless consumer of claret, an overindulgence in books could have devastating consequences for the mind and body.

Across his essay, Tissot offers hundreds of examples of men who read too much, studied too hard, and consumed knowledge to the point of madness. There is the young man who developed an allergy to reading: “if he read even a few pages, he was torn with convulsions of the muscles of the head and face, which assumed the appearance of ropes stretched very tight.” And the man whose laser focus effected hair removal: “his beard fell first, then his eye-lashes, then his eye-brows, then the hair on his head, and finally all the hairs of his body”. There is Nicolas Malebranche, who was gripped with “dreadful palpitations” upon looking into Descartes’ Treatise on Man, and an unnamed Parisian rhetorician, who “fainted away whilst he was perusing some of the sublime passages of Homer.” There is the blind Constantius Huygens, whose “immoderate studies so broke the force of his sensorium, that he thought his body was made of butter”. Huygens found himself very cold, shunning the fire “lest it should melt him”, and tragically ended his life by leaping into a well. And there “have been many instances of persons, who thought themselves metamorphosed into lanterns, and who complained of having lost their thighs.” ※

What is the cause of these afflictions? The reason men “grow pale with poring over books”? Some of Tissot’s prescriptions are those that physicians still endorse to combat the ills of deskwork: frequent exercise, enough sleep, good ventilation, proper posture and hygiene, avoiding the “excesses of gluttony”. And others, while based on long outdated models of the mind, feel relevant in our era of “dopamine fasting” and “digital detoxes”. Much of Tissot’s essay treats the nerves like electrical wires carrying too much current, which become gradually calcified by literary amperage — a kind of downregulation of neurotransmitters avant la lettre. As such, it is not the physical act of reading, but the quality of reading material that poses a danger.

It is universally known that there are books composed without any strength of genius, which appear quite insipid and unaffecting to the reader, and only tire the eyes; but those that are composed 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 complete, lasting, and frequent it is, breaks the man the more.

Unlike later moral panics about the corrupting effects of fiction on female readers, here it is paradoxically the most praiseworthy material that produces the most lamentable results. Elsewhere, Tissot turns to humoral models of the nerves, where the “body is exhausted by too great an evacuation”. Suppose “the blood were to run copiously from a wound”, or “the gastric fluids were to be poured forth by the anus”, or “the breasts sucked too long”, or “a greater discharge of saliva made by spitting”, he writes. In all cases, “strength would decline, and the health be lost”. For studious men, an equivalent expenditure takes place in the brain: “a perpetual dissipation of the nervous fluid springs from the incessant action of the nerves”.

Tissot was not the only person concerned with longevity and the life of the mind in this period. Robert Priestly issued a 1798 treatise examining the conditions of “the sedentary” alongside “persons of fashion”. During the “Amusements of the Learned” section of his Curiosities of Literature (1791–1823), Isaac D’Israeli describes how a “continuity of labour deadens the soul”, and tells of various scholars’ methods for kicking back. Descartes kept a garden, Petavius twirled his chair for five minutes at the end of every second hour, and “Spinosa would mix with the family-party where he lodged, and join in the most trivial conversations, or unbend his mind by setting spiders to fight each other”. In the Georgian era, Chandler Robbins’ Remarks on the Disorders of Literary Men (1825) and George Hayward’s A Lecture on Some of the Diseases of a Literary Life (1833) picked up where Tissot left off, elaborating preventive measures and rehabilitating programs for those “who injure themselves by study”.

And yet, there are moments in Tissot’s essay that suggest a quieter agenda. Above all else, he seems concerned with solitude — not only as a precipitating condition of melancholy, but also as a threatening attitude of self-absorbed autonomy. He enjoins his reader to “be vigilant” toward the studious and “knock at their doors; rouse them from their lethargy; make them, whether they will or no, lay aside their studies”. As Christine Crockett Sharp writes, Tissot’s depiction of “the mental ravages one would experience by indulging in such solitary pursuits” was linked to a conception that it degraded a kind of biopolitical function: the ability “to make reasonable and moral decisions” and fulfill “gendered expectations regarding propagation and the success of eventual offspring”. Very little attention is paid to writing in An Essay on Diseases Incidental to Literary and Sedentary Persons — it is the bookworm, absorbing all the world’s learning and fathering nothing productive, who most concerns Tissot. Perhaps it’s not surprising, then, that the figure of “the man of letters” appeared in the Swiss physician’s earlier work on Onanism (1766). “The masturbator, entirely devoted to his filthy meditations, is subject to the same disorders as the man of letters, who fixes his attention upon a single question”.