18th–Century Medical Theory

Page 5 of 12

John Brown, M.D. (1735-1788)

John Brown's portrait supported by a monument

Library, College of Physicians of Philadelphia

Engraving by William Blake (1757-1827) from The Elements of Medicine (London, 1795), Frontispiece. Guy's Hospital Physical Society Collection R128.7 BRO.

Rush made some important contributions to medicine. He is considered the father of psychiatry in America because of his Medical Inquiries and Observations upon the Diseases of the Mind (1812), the first book on mental diseases published in the United States. Rush may be best known, however, for his advocacy of "heroic therapeutics," a treatment that involved much purging and bloodletting.

As stated earlier, William Cullen's ideas had a great effect on Rush in medical school and his beginning practice. Cullen was a solidist, believed in limited bloodletting, purging, and vomiting, and that moderation and balance were the keys to successful treatment.1 Among the factors Cullen said caused fevers were strong emotion and intemperance. Fevers could also arise from remote causes: contagions coming from other people with the disease and miasmata from such places as marshes (that is, non-human sources). Only attacking the debility caused by the disease or hygenic preventive measures were possible.

Cullen believed in disease entities (which is not to say he understood the germ theory). Thus, he compiled an extensive nosology—a classification system for diseases.2 Also, Cullen expected that morbid anatomy (linking post-mortem conditions with clinical histories) as practiced by the great Giovanni Morgagni (1682-1771) would help in disease identification.3

One aspect of Cullen's theory that survived in Rush's mature ideas was the belief that miasmata had a role in disease (for Rush, as a predisposing cause). Also Rush maintained an essentially solidist orientation in his concepts; however, as his career progressed, he largely broke from Cullen's ideas.

The most important writer among those who spurred Rush's break with Cullenism was John Brown. Brown dismissed any notion of diseases as separate entities and classification schemes useless. He thought pathological anatomy showed only changeable forms of the disease and not the underlying cause.

Brown postulated the fundamental biologic principle of excitability. All living matter had it. Excitability was "a capacity to perceive impressions and be able to respond to them."4 External stimuli act upon excitability, and the combined response of stimuli and excitability is called excitement. Predisposition to disease (the state before the occurrence of disease) occurs when there are too many stimuli, causing excitability to decrease, or too few stimuli, causing excitability to increase. Excessive stimulation is called the sthenic state. Sthenic disease occurs when an overabundance of stimuli dangerously exhausts excitability, thereby creating an overabundance of excitement. This pathological state is called indirect debility. Deficient stimulation is called the asthenic state. Asthenic disease occurs when a deficiency of stimuli reduces excitement and results in "an accumulation of unused excitability."5 This pathological state is called direct debility.

The Brunonian system has several consequences for the practitioner. One is that a physician is responsible for the general health of a patient as well as for restoring equilibrium between excitability and outside stimuli. A second consequence is that it is only minimally necessary to distinguish precipitating—also called proximate—causes of disease. Only the general predisposing factors are important for the practitioner to determine.6

Another consequence is that the practitioner doesn't need to be concerned with specific diagnoses, for clinical history or signs of disease. As Risse has written, for the Brunonian physician, "there is but one general disease with a variety of forms, and one general pathological condition resulting from excessive or deficient excitement."7 The physician need only take the arterial pulse (the only reliable diagnostic procedure) and determine what stimulants the patient has received prior to becoming sick in order to prescribe treatment.

Treatment itself was relatively straightforward. In sthenic diseases, the effects of stimuli need to be lessened. Acceptable therapy included gentle cathartics, a vegetarian diet, watery drinks, and bleeding "only in the most violent cases." In asthenic diseases, excitement needs to be increased, so rich foods, liquor, camphor, and opium are used.8

Brown treated his gout as an asthenic disease, and as Lester King so pungently puts it, "Evidence is not at all clear that he cured himself of gout, but it is well established that he became heavily addicted to alcohol and opium."9

Brown's system has at least one more modern aspect to it. He fully emphasized how the body is subject to interaction with outside stimuli, a notion in basic accord with modern ideas of, say, how an unhealthy environment or poor food choices affect our health. The key point is, however, that Brown's therapy is seen as supporting the system rather than depleting it.


1. Christopher Clayson, "William Cullen in Eighteenth Century Medicine." In William Cullen and the Eighteenth Century Medical World, A. Doig, et al., eds., Edinburgh, Edinburgh University Press, 1993, 95.

2. Lester King, The Medical World of the Eighteenth Century (Chicago University Press, 1958), 139-142.

3. Richard H. Shryock, Medicine and Society in America: 1660-1860 (Ithaca, NY: Cornell University Press, 1972), 68.

4. Günther Risse, "The Brownian System of Medicine: Its Theoretical and Practical Implications," Clio Medica, vol. 5, 1970, 45.

5. Ibid., 46.

6. Ibid.

7. Ibid., 47.

8. Ibid., 48.

9. King, 143-44.

Funded in part by a grant from the National Park Service, Challenge Cost Share Program