Hoffmann, Friedrich

Hoffmann, Friedrich

(b. Halle, Germany, 19 February 1660; d. Halle, 12 November 1742)

medicine, chemistry.

Hoffmann was a leading medical systmatist of the first half of the eighteenth century. Although not a notably original thinker, he became a highly influential teacher and practicing physician in Germany, systematizing coherently the Galenic, iatromechanical, and iatrochemical aspects of the phenomena of health and disease. The attention he focused on the role of the nervous system in physiology and pathogenesis contributed to a gradual shift in medical approach, namely from preoccupation with so-called humors and vascular hydrodynamics to that with neuromuscular action and sensibility. This transformation was reflected in the subsequent medical systems of Cullen and John Brown.

Hoffmann (often called “the younger” to distinguish him from his father) was the son of a well-known municipal physician of Halle, who guided him during his early anatomical and chemical studies. In 1678 the younger Hoffmann went to Jena, where he studied medicine for two years under the direction of Wedel. His interest in chemistry lured him for a short period to Erfurt, where he attended the chemistry lectures of Cramer. In 1681 he received his M.D. from the University of Jena and was allowed to teach there. But the subsequent success of Hoffmann’s chemistry lectures reportedly provoked the jealously of Jena’s senior faculty, and the young physician soon left for the city of Minden, where his brother-in-law provided him with an official, salaried position. Two years later, to become acquainted with the activities and methods of other European colleagues, Hoffmann embarked on a tour of Belgium, Holland, and England, where he met Boyle. He returned to the Continent in 1684 and began a successful medical career in the principality of Minden, and in 1688 was named provincial physician for Halberstadt, Saxony, famous for its mineral waters.

In 1693 Frederick III, elector of Brandenburg, chose Hoffmann to become the first professor of medicine at the new University of Halle. Haffmann was also charged with the organization of the medical school, and his success in the new institution was immediate. His lectures on physics, chemistry, anatomy, surgery, and the practice of medicine attracted a great number of both students and physicians. Given the privilege of selecting a second professor of medicine, he brought to the university in 1694 a former fellow student at Jena, Georg Stahl, originator of the phlogiston theory.

In 1709 Hoffmann was called to Berlin by Frederick I to become the ruler’s personal physician. He remained only three years at the court, which was oppressively beset with petty intriguing. After extricating himself from this situation, Hoffmann returned to Halle to resume teaching and medical practice. In 1734 Hoffmann was again summoned to the Prussian court, owing to the recommendation of Boerhaave; as physician he served Frederick William I for about eight months and then returned to Halle.

Hoffmann was a fellow of the Royal Society of London and a member of the Berlin Academy of Sciences, and in 1735 was elected to the Imperial Russian Academy of Sciences in St. Petersburg. In his last years he suffered from a pulmonary ailment, which curtailed his activities and led to his death at the age of eighty-two.

From the time of Hippocrates, physicians had sought to discover and establish the fundamental laws governing the phenomena of health and sickness. It was long believed that medicine would become a truly scientific endeavor, rather than a purely empirical craft, only through the apprehension of rational causes and an understanding of the mechanisms producing disease. This outlook led in time to formulation of an elaborate paradigm of so-called balanced and corruptible humors. For about 2,000 years this formulation sufficed to explain all of physiology and pathology.

As the Galenic concepts of soul, spirit, and faculty became obsolete in the seventeenth century, a new theoretical foundation was needed that would incorporate Harvey’s theory of the circulation of the blood, new microscopic observations, and the recent discoveries in physics. Following the influential method of Cartesian mechanical philosophy, physicians began to consider the human body as a machine having constituent particles in constant motion. Hoffmann believed that the laws of mechanics could also explain the normal and pathological changes occurring in an organism. He attempted to interpret the new knowledge according to the physiological ideas of Descartes and thereby to establish a firm theoretical basis for medicine: a system of general principles capable of explaining all physiological phenomena.

For Hoffmann the organism was a machine composed of fluid and solid particles. The fluids-blood, lymph, and animal spirits-provided the continuous and appropriate movements necessary for life; hence, normal and abnormal qualities of the humors and organs were due to various kinds of chemical particles which were distributed in different proportions. The animal spirits, for example, were visualized by Hoffmann as volatile, ethereal corpuscles of matter flowing through the nervous system.

To explain the functions of the body, Hoffmann relied heavily on the Cartesian hydrodynamic schemes. According to these, the various humors flowed through the body’s vessels at different rates, depending upon the diameter of the vessels. Pulsations observable on the surface of the cerebral membranes were taken as proof of the circulation of the animal spirits.

Hoffmann considered the fine material particles that constituted the “nerve spirits” to be the principal movers of the body, conferring the necessary vital motions to all other bodily fluids and solids. In these activities the ethereal spirits were directed by an anima, or sensitive soul, which Hoffmann conceived of as a subtle, hypothetical form of matter on which God himself had directly impressed motion. Responsible, in an Aristotelian sense, for the form of the body, this soul, or “nature,” possessed mechanical powers, or virtues, responsible for the purposeful and apparently goal-directed activities of the organism; moreover, it constituted the material link with the immaterial and rational human mind created by God. Hoffmann thus seems to have provided a Neoplatonic scheme, establishing a hypothetical chain of entities between the divine mind and the coarse particles of the body and thereby bridging the strict Cartesian dualism of spirit and matter.

The anima was therefore for Hoffmann the first principle of motion, the directive force using the animal spirits as instruments for all vital motions, including automatic and coordinating functions. Among the powers communicated to the nervous spirits was a plastic, organizing capability that controlled nutritive processes and orderly growth.

Kurt Sprengel believed that Hoffmann had been profoundly influenced by Leibniz, who was a friend, in his conception of the animal spirits. Accordingly, Sprengel tried to interpret Hoffmann’s ethereal spirits as veritable aggregates of monads which directed and coordinated their own activities according to a general plan. Hoffmann, on the other hand, envisioned animal spirits as being composed strictly of material particles, empowered by God to perform motions through mediation of the sensitive soul. In this sense, the animal spirits did carry out specific movements, in accordance with certain divinely impressed “ideas,” for the preservation and normal development of the organism.

Hoffmann considered the fibers forming the vessels, heart, and muscles to have just the degree of elasticity of tension needed for optimal blood circulation. Tone in the fibers could also be influenced by the animal spirits, he held, rather than being dependent solely on immanent physical cohesiveness.

To Hoffmann, the prerequisite for good health was proper circulation of the humors, attributable to normal tension or tonus in all the fibers. Disease, on the other hand, was the result of distorted vital actions arising from impaired humoral motions and resultant changes in the solid parts of the body. Drawing upon hydrodynamic concepts, he explained a series of pathological changes as being the result of defective circulation, which in turn caused humoral obstructions and stagnations. Many of these disturbances were caused by abnormal motions of the ethereal animal spirits. These spirits increased the tone of certain fibers, producing vascular and intestinal spasms or a diminished fiber tension called atony. According to Hoffmann, local humoral stagnations led in turn to a series of chemical changes responsible for many local lesions. In addition, certain diseaseproducing environmental factors were brought into the body with inspired air. Hoffmann hypothesized that these miasmas, contagions, and poisonous vapors created primarily a series of blood abnormalities.

In a state of disease, the fluid and solid parts of the human machine appeared to influence each other through a consensio, or “sympathy,” between certain organs and humors, mediated largely by the animal spirits flowing through the nerves; thus were explained certain systemic reactions to local disturbances, and vice versa.

Hoffmann’s system, although extremely hypothetical, replaced in great part that of the older Aristotelian-Galenic faculties, qualities, and spirits. He followed closely the corpuscular views of contemporary physics and chemistry and tried to interpret physiology and pathogenesis strictly in terms of matter and motion. To be sure, Hoffmann’s explanations, couched in a new language, were still largely based on the older views. But the view that certain biological processes occurred in a well-coordinated and goal-directed fashion seemed incompatible with the known, contemporary mechanical models, and Hoffmann answered these difficulties by asserting that all unexplainable phenomena responded to a higher form of physics not as yet discovered.

Although its effect on the practice of medicine was then small, Hoffmann’s system provided a basis on which further medical ideas and hypotheses could be formulated. His formulations of a series of general principles for understanding the human organism, as well as the formulations of other eighteenth-century systematists, led to the more precise investigations that laid the theoretical foundations of modern medicine.

Hoffmann maintained a lifelong interest in chemistry. His primary contributions here were in the investigation of mineral waters, specifically in improving contemporary analytical methods and distinguishing essential components. Hoffmann studied spiritus mineralis (carbon dioxide) in water, which he characterized as a weak acid intermixed with various salts. He also discerned the presence of sulfates in certain waters and clearly separated magnesia from lime. The hot springs of Carlsbad especially interested Hoffmann, who explained that the high temperatures of the waters were caused by a chemical reaction involving sulfur, iron, and oils. Another of his studies, having clear medical implications, was his description of carbon-monoxide poisoning from the fumes of burning charcoal (1716).

While taking substantial issue with Stahl’s medical theory, Hoffmann accepted many of his chemical ideas, one exception being that of the existence of phlogiston in metals. Denying phlogiston, Hoffmann held that a calx was formed by the action of acids on metals.

In his work on therapeutic applications of chemical substances, Hoffmann mixed one part ether (acidum vitrioli vinosum) with three parts alcohol to create “liquor anodynus minerali Hoffmanni,” or “Hoffmann’s drops,” which became a popular medical panacea.

BIBLIOGRAPHY

I. Original Works. Hoffmann’s voluminous writings have been collected in Opera omnia physico-medica, (Geneva, 1740), 6 vols. The first 3 vols. of this compilation contain his most important medical work, the Medicinae rationalis systematicae, originally published in 2 vols. (Halle, 1718–1720). The last 3 vols. of the Opera omnia include articles and monographs on medical consultations, chemical analyses, and therapeutical indications.

The first Operum omnium physico-medicorum supplementum (Geneva, 1754) appeared in 2 pts. This supp. vol. contains some of Hoffmann’s famous works, such as Medicus politicus (pp. 389–422), the Commentarius de differentia inter Friderici Hoffmanni doctrinam medico-mechanicam et Georgii Ernest Stahlii medico organicam (pp. 423–499), and his 1695 work Fundamenta medicinae ex principiis naturae mechanicis (pp. 633–676).

The second and last supplement, Operum omnium physico-medicorum supplementum secundum (Geneva, 1760), appeared in 3 pts. It contains Hoffmann’s Opuscula physicomedica varii argumenti and other therapeutical and chemical works.

Among the more important writings of Hoffmann available in other languages are his clinical collection Medicina consultatoria, worinnen unterschiedliche ueber einige schwehre Casus ausgearbeitete Consilia, auch Responsa Facultatis Medicae, 2 vols., 10 pts. (Halle, 1721–1733); and the treatise on mineral waters, Gruendlicher Bericht von der herrlichen Wuerckung, vortrefflichen Nutzen und rechtem Gebrauch des zu Sedlitz in Boehmen neu entdeckten bittern purgierenden Brunnens (Halle, 1725). There is also a German trans. by Auerbach, Politischer Medicus, oder Klugheitsregeln, nach welchen ein junger Medicus seine Studia und Lebensart einrichten soll (Leipzig, 1753).

In France, Jacques-Jean Bruhier translated into French Hoffmann’s Medicinae as La médecine raisonnée (Paris, 1739) and the Medicus politicus as La politique du medécin (Paris, 1751).

In English an abridged trans. of certain parts of the Medicinae concerning fevers, hemorrhages, and spasmodic and atonic diseases was published as A System of the Practice of Medicine, 2 vols. (London, 1783), trans. by William Lewis, revised and completed by Andrew Duncan, 2 vols. (London, 1783). On mineral waters see New Experiments and Observations Upon Mineral Waters, Directing Their Farther use for the Preservation of Health and the Cure of Diseases, 2nd ed. (London, 1743), extracted from Hoffmanr’s essays on the subject and illustrated with notes by Peter Shaw. Also available is A Dissertation on Endemial Diseases, or Those Disorders Which Arise From Particular Climates, Situations and Methods of Living, trans. (with preface and appendix) by R. James (London, 1746). There is also a small monograph, A Treatise on the Teeth, Their Disorders and Cure (London, 1753), a trans. of Historia dentium physiologicae et pathologicae pertractata (Halle, 1698). See also Lester S. King’s trans. of Hoffmann’s Fundamenta medicinae (London-New York, 1971).

II. Secondary Literature. The standard biography on Hoffmann is Johann H. Schulze, Commentarius de vita Friderici Hoffmanni, included in Opera Omnia, I, i-xiv. Shorter biographical sketches can be found in A. Hirsch, Biographisches Lexikon der hervorragenden Aerzte aller Zeiten and Voelker, 3rd (unchanged) ed., III (Munich, 1962), 256–259, and A. J. L. Jourdan, ed., Biographie médicale, Dictionnaire des sciences médicales, V (1822), 239–257. The latter contains a complete list of Hoffmann’s writings. Additional biographical documents are W. Piechocki, “Das Testament des Halleschen Klinikers Friedrich Hoffmann des Juengeren (1660–1742),” in Acta Historica Leopoldina 2 (1965), 107–144; and G. Mamlock, “Koenig Friedrich Wilhelm I Briefe an den Hallenser Kliniker Friedrich Hoffmann,” in Deutsche medizinische Wochenschrift, 37 , no. 48 (1911), 2242–2244.

Two comprehensive summaries of Hoffmann’s medical system and therapeutics can be found in Kurt Sprengel, Versuch einer pragmatischen Geschichte der Arzneikunde (Halle, 1803), pt. 5, pp. 118–148; and Heinrich Haeser, Lehrbuch der Geschichte der Medizin und der epidemischen Krankheiten, 3rd ed., II (Jena, 1881), 509–519. Another perceptive sketch is Paul Diepgen, “Zum 275. Geburstage Friedrich Hoffmanns,” in Deutsche medizinische Wochenschrift, 61 no. 10 (1935), 389–390.

Indispensable for an understanding of Hoffmann’s medical ideas are the recent publications in English by King. Among them is The Growth of Medical Thought (Chicago, 1963), ch. 4, pt. 4, pp. 159–174, which deals with Hoffmann’s main ideas as expressed in the Medicinae. An analysis of Hoffmann’s earlier work appeared in King, “Medicine in 1965: Friedrich Hoffmann’s Fundamenta Medicinae,” in Bulletin of the History of Medicine, 43 (1969), 17–29, and in his The Road to Medical Enlightenment 1650–1695 (London-New York, 1970), ch. 5, pp. 181–204. For a comparison of Hoffmann and Stahl see King, “Stahl and Hoffmann: A Study in Eighteenth-Century Animism,” in Journal of the History of Medicine and Allied Sciences, 19 (1964), 118–130.

Hoffmann’s chemical contributions have been summarized in Johann F. Gmelin, Geschichte der Chemie, II (Göttingen, 1798), 170–189, which lists 122 separate chemical publications. A more recent and valuable summary of Hoffmann as a chemist appeared in J. R. Partington, A History of Chemistry, II (London, 1961), ch. 19. 691–700.

For an examination of Hoffmann’s theological interests see Werner Leibbrand, Der goettliche Stab des Aeskulap, 3rd ed. (Salzburg, 1939), ch. 13, pp. 230–236.

Guenter B. Risse