“I shall use my talents to aid the sick to the best of my capabilities and discernment; I shall refrain from wrongdoing or harming any person.” Hippocratic author of The Oath

The medicine of Jefferson’s day had advanced much from ancient times, but it still labored under the ancient theory of bodily humors (chumoi, “juices” or “flavors”)—bile and phlegm, according to the Hippocratic authors of Affections and Diseases; blood, phlegm, bile, and black bile, according to the Hippocratic author (probably Polybius) of The Nature of Man and to Galen centuries later (b. 129 A.D.)—so a few words on ancient medical practice are needed.

There were many schools of thought in ancient medical practice. Schools of medicine lined up theoretically with schools of philosophy—e.g., Asclepiadean practice with Epicurean atomism, Methodism with Pyrrhonic Skepticism, Pneumatism with Stoicism, and Eclecticism with philosophical eclecticism—and there were vigorous debates between the schools. Alignment dictated theoretical orientation to medical practice, though the general conceptions of disease and health were same.

Comparable to the notion of vice being a sort of unhealth or imbalance of the soul (equanimity) found in Plato, Aristotle, Epicurus, and the Stoics, disease for ancient physicians was believed to be a perturbation or imbalance of the physical body. Remedy, therefore, included bringing the body back into physical balance—for humoral practitioners, riddance of excess, or accretion of defect, of blood, phlegm, bile, or black bile. “Health is chiefly that state in which the constituent bodily substances are rightly proportioned in strength and number to each other and are well mixed” (The Nature of Man; my translations). Practitioners had to know not only the human body, but also the seasons of the year, the winds endemic to a particular locality, and “the effect of water on health” (Airs, Waters, Places). There was general recognition that medicine was a science (techne, to be taken broadly as “craft” or “skill”—i.e., something implying method and use of rationality) in its infancy, and that though theory would sometimes dictate praxis, theory generally had to yield to praxis—viz., to careful observation of the natural course of a disease. The author of Prognosis states that a physician must study a patient’s face (e.g., “if the eyes shun the glare of light or if they involuntarily weep”), the manner of sleeping, bowel movements, appetite, posture, breathing, and temperature. Methods of treatment were blood-letting, expurgation, emetics, suppositories, bathing, plastery, ointments, surgery, and especially regimen (exercise and diet).

One substratal division, found in early Hippocratic medical writings and in the writings of Galen, concerns two different approaches to the practice of medicine: dogmatism (or rationalism) and empiricism. dogmatists insisted on ascertaining the causes (aitiai) of a disease to direct efforts to cure patients. “Every symptom will be found to have some cause, and if it has a cause, fortuity can be no more than an unknown word” (The Science of Medicine). They employed principles (dogmata) such as “opposites cure opposites,” “each disease has a natural cause,” and causes of disease beyond what is apparent to sight must be ascertained through inferential reasoning (logismos). Empiricists, using experience (empeiria), were content to use past personal experience of similar cases, reports of other doctors, hunches, and even dreams to direct efforts at cure. Both dogmatists and empiricists, acknowledging medicine as a science, probably acknowledged as well that all diseases were in principle curable, but neither dared to vaunt that its methods were anything close to infallible. “I warmly recommend a doctor who makes small errors. Infallibility is only infrequently seen” (Ancient Medicine). Stated succinctly in Aphorisms, “Life is short; science is long.” Such differences conceded, the practice of dogmatic medicine and that of empirical medicine were more similar than dissimilar (Ancient Medicine).

Thomas Jefferson, in keeping with the empiricism of his day, disdained dogmatic medicine. Empirically driven, he was interested more in results than in explanation. He writes to Dr. Edward Jenner (14 May 1806), “Harvey’s discovery of the circulation of the blood was a beautiful addition to our knowledge of the animal economy, but on a review of the practice of medicine before & since that epoch, I do not see any great amelioration which has been derived from that discovery, [while] you have erased from the Calendar of human afflictions one of it’s greatest.”

Fullest expression of Jefferson’s detestation of dogmatic medical practice is in a noteworthy letter to Dr. Caspar Wistar (21 June 1807). It contains the germ of Jefferson’s philosophy of medicine.

Jefferson begins by stating that nature is the proto-physician. Animals’ bodily organs and functions are “subject to derangement,” which induces pains and tends to their destruction. “In this disordered state,” he continues, “we observe nature providing for the re-establishment of order, by exciting some salutary evacuation of the morbific matter, or by some other operation which escapes our imperfect senses and researches. She brings on a crisis, by stools, vomiting, sweat, urine, expectoration, bleeding, &c., which, for the most part, ends in the restoration of healthy action.” Jefferson’s language is Hippocratic/Galenic.

The most successful physicians over time have learned to follow nature. “Experience has taught us,” Jefferson asserts, “that there are certain substances, by which, applied to the living body, internally or externally, we can at will produce these same evacuations, and thus do, in a short time, what nature would do but slowly, and do effectually, what perhaps she would not have strength to accomplish.” If a disease, characterized by specific symptoms, is overcome, say, by a natural evacuation, then “whenever that disease recurs under the same appearances, we may reasonably count on producing a solution of it, by the use of such substances as we have found produce the same evacuations or movement”—bloated stomach, by emetics; intestinal problems, by purgatives; inflammation, by bleeding; syphilis, by mercury; and watchfulness, by opium; inter alia. “So far,” he states, “I bow to the utility of medicine.”

“But the disorders of the animal body, & the symptoms indicating them, are as various as the elements of which the body is composed.” Moreover, the combinations of symptoms are “infinitely diversified,” and many combinations of symptoms are so rarely seen that many diseases go unnoticed. “To an unknown disease,” says Jefferson, “there cannot be a known remedy.”

How, then, is a physician to proceed in such complex, enigmatic cases?

Jefferson’s answer is greatly in keeping with ancient empirical medical practice, in which “observations of the past” begin one’s researches and principles do not guide therapy. Writes the author of Ancient Medicine: “I am utterly at a loss to know how those who prefer theoretical arguments and who reduce the science of medicine to an incomplex matter of ‘principles’ ever cure anyone.” In complex cases, theory is superincumbent, and not practicable. Jefferson writes similarly, “Here, then, the judicious, the moral, the humane physician should stop” and let nature doctor. A physician ought to trust nature, rather than “hazard … a greater derangement of the system by conjectural experiments on a machine so complicated & so unknown as the human body, & a subject so sacred as human life.” In such cases, appeal to theory is bound to have toxic consequences.

If a physician wishes to act, let a placebo be the panpharmacon. “One of the most successful physicians I have ever known, has assured me, that he used more bread pills, drops of colored water, & powders of hickory ashes, than of all other medicines put together. It was certainly a pious fraud.”

In contrast, “the adventurous physician,” Jefferson continues,

substitutes presumption for knolege. From the scanty field of what is known, he launches into the boundless region of what is unknown. He establishes for his guide some fanciful theory of corpuscular attraction, of chemical agency, of mechanical powers, of stimuli, of irritability accumulated or exhausted, of depletion by the lancet & repletion by mercury, or some other ingenious dream, which lets him into all nature’s secrets at short hand. On the principle which he thus assumes, he forms his table of nosology, arrays his diseases into families, and extends his curative treatment, by analogy, to all the cases he has thus arbitrarily marshalled together.

A young practitioner must not be adventurous. Instead, he must learn the “real limits of his art.” In complex cases, “his office is to be a watchful, but quiet spectator of the operations of nature,” not a pathfinder or conquistador, for “the only sure foundations of medicine are, an intimate knolege of the human body, and observation on the effects of medicinal substances on that.”

Jefferson concludes: “The inexperienced & presumptuous band of medical tyros let loose upon the world, destroys more of human life in one year, than all the Robinhoods, Cartouches, & Macheaths do in a century. It is in this part of medicine that I wish to see a reform, an abandonment of hypothesis for sober facts, the first degree of value set on clinical observation, and the lowest on visionary theories.”