STAHL, GEORG ERNST

(b. Ansbach, Germany, 21 October 1660 [1659?]; d. Berlin, Germany, 4 May 1734)

medicine, chemistry.

Stahl has aroused much controversy. As a physician he was outstanding; he held the highest academic positions, enjoyed a very active practice, and through his writings became vastly influential. As a philosopher he supported the viewpoint known as vitalism and wove that concept into the fabric of his medical system. As a chemist he elaborated and maintained the doctrine of phlogiston, which, until outgrown later in the eighteenth century, provided a reasoned explanation for many chemical phenomena. But his teachings, particularly his stand on vitalism, in large part ran counter to the trend of the times; his chemical theories were overthrown; his vitalist doctrine, in the form that he elaborated it, could not stand up against the onrushing tide of research and experimentation: while his system of medical practice faded away before numerous competitors. Furthermore, his personality was often antagonistic, his style of writing obscure and hard to understand. Yet, even though he seemed to be discredited, Stahl influenced the whole of eighteenth-century medicine; and his imprint is being increasingly appreciated as historians trace his role in the drama of eighteenthcentury medical thought.

Although the generally accepted date of Stahl’s birth is 21 October 1660, Gottlieb disputes this and claims that the baptismal register, in the parish of St. John in Ansbach, shows 1659. There is little information about Stahl’s early life. Even as a youth he had considerable interest in chemistry. He studied medicine at Jena and received his degree in January 1684. He then devoted himself to scientific work and lectured in chemistry at the university, attaining considerable reputation. In 1687 Stahl was invited to become court physician at Weimar, where he remained for seven years. He subsequently joined the medical faculty of the new University of Halle.

Elector Frederick III of Brandenburg (Frederick I of Prussia), eager to surpass his neighbors, decided to establish a new university at Halle. The great liberal jurist Christian Thomasius. who had been expelled from Leipzig, settled at Halle at Frederick’s invitation. The elector built his university around Thomasius and attracted such men as August Francke in oriental languages and Friedrich Hoffmann in medicine. In 1693 the university received the imperial privilege and was officially inaugurated in 1694.

Hoffmann, needing help, was instrumental in securing Stahl’s appointment as the second professor of medicine. In 1694 Stahl went to Halle, where he remained until 1715, lecturing particularly on the theory of medicine and on chemistry. Hoffmann and Stahl, although different in many respects, formed a very strong faculty. and Halle became a leading medical school. In 1715, at the request of Frederick William I of Prussia, Stahl left Halle and went to Berlin to be court physician. He remained there until his death.

Stahl’s personality has received much unfavorable comment. He has been condemned as misanthropic and harsh, narrow-minded and intolerant. These qualities also have been contrasted unfavorably with the sunnier and more open disposition of Hoffmann. Much of the evaluation rests on rather slender evidence and stems particularly from the statements of Haller, which many historians have repeated. On the other hand, Stahl had many defenders. The truth is virtually impossible to establish, unless further primary source material should be discovered.

Stahl was a devout Pietist —Halle, in the early days, was the center for Pietism as well as rationalism and this background undoubtedly colored his doctrines. Many misfortunes attended his personal life. His first wife died in 1696 of puerperal fever and his second wife in 1706, of the same disease. A daughter died in 1708. These were the years of his greatest productivity, and it is only reasonable to see in his outward attitudes some reflection of his personal life. He was a prodigious worker, and pride and self-confidence apparently were notable qualities. Gottlieb quotes Stahl’s personal motto as E rebus quantumcumque dubiis quicquid maxima sententium turba defendit, error est. for which I suggest the translation, “Where there is doubt, whatever the greatest mass of opinion maintains. . . is wrong.”

Stahl’s style of writing is prolix and convoluted, and difficult to understand. Perhaps the style is the man himself.

Stahl, who lived well into the eighteenth century, was nevertheless part of the seventeenth-century rebellion against tradition; and his doctrines reflect, in a way, the intense turmoil of that period. The rebellion, of course, involved all phases of intellectual life. In medicine the Galenic theories, which rested largely on Aristotle, had come under severe attack. In astronomy and physics, especially mechanics, new experimental methods had shown how untenable were the older views. In physiology and biology Harvey was the greatest among many investigators who introduced new concepts that were firmly grounded on empirical demonstration. In philosophy Descartes offered new vistas and new methodology, while Gassendi helped to reintroduce atomism. In chemistry the arch-rebel Paracelsus had given great impetus to a movement of which the leading representatives were van Helmont, in the early seventeenth century, and Sylvius and Willis in the later part. At the same time traditional religion remained powerful and entrenched. Piety and orthodoxy were strong values, and atheism and materialism were epithets dreaded by most scientific workers. The new philosophy and the new science, which threatened orthodox religions, had to come to terms with religious tenets.

In the medical world of the later seventeenth century, many different theories competed actively; but no clear victory was in sight for any one. The traditional Galenic theories were in retreat but by no means annihilated. latrophysicists tried to explain all medical phenomena on the basis of matter, motion, and the simple laws of mechanics; iatrochemists relied on the chemical “principles” as their explanatory terms. The dichotomy between mind and body had taken deep root and was influencing medical theory, while the close relation between the “mind” of medical doctrine and the “soul” of religious orthodoxy was troublesome indeed.

Although Stahl did not provide any straightforward or systematic exposition of his doctrines, his prolix writing contains certain recurrent themes that serve as a foundation for his more specific discussions. Foremost among his basic concepts is the irreducible difference between the living and the nonliving. Mind and matter are distinct and ultimate. Matter, particulate in its nature, exists as a real entity in its own right and comprises the material aspect of the universe. But equally real and equally deserving of the designation ens are the immaterial aspects, of which the anima is the key manifestation. While both the living and the nonliving are composed of matter, only living creatures have an anima. The immaterial vital principle serves as the ultimate differential feature that distinguishes the living from the nonliving.

A second major principle involves the concept of goal or purpose. The philosopher (or scientist) who tries to describe and explain the phenomena of life must take account of the goal activity. Behavior is not blind or mechanical. Living creatures can be understood only if we pay attention to their striving toward particular ends or purposes. This striving, in turn, implies a directive agency controlling the goal-seeking effort. The agent is the anima.

A third principle concerns the place of mechanism in the scheme of things. All nonliving creatures-the inorganic or “mixed” — are entirely mechanical. Living creatures, up to a point, also are mechanical; but the mechanism involved represents only the instrument of the directing agent or anima. The agent exerts itself, manifests itself, through mechanical principles.

These major doctrines give rise to certain corollaries: the anima that directs the purposive activities of the body acts in an intelligent fashion. It is rational and exhibits foresight to bring about the desired ends. Furthermore, the directing force can be understood only as a process involving a time span. It implies wholes rather than parts, and only a false philosophy will focus exclusively on the parts and neglect the whole.

On this framework Stahl elaborated a rather detailed and intricate, if rambling and untidy, superstructure. The entire doctrine of animism rests on the ultimate distinction between the living and the nonliving. Stahl pointed out certain significant differences — the nonliving, which may be either homogeneous or heterogeneous, is relatively inert, remains stable over an indefinite time span, and is not readily changed or decomposed. Living creatures, however, are always heterogeneous and always have a great tendency to decomposition and putrefaction. Yet the components of the living body, despite this tendency to putrefaction, remain stable over the limited time that life persists. The tendency to decomposition is held in check by a conserving agent. This agent, the essence of life, is the anima, which thus preserves the body from corruption.

The living body depends on motion — most obviously the motion of the heart and the circulation of the blood. The anima exerts its control over the body through this very property of motion. By using this concept Stahl engages in some remarkable semantic juggling that enables him to construct a formal and orderly system.

He explicitly denies that motion is in any sense a function of matter. Although material objects do exhibit motion, this property is not intrinsic to them. On the contrary, matter-consisting of material particles-is inert; motion is something added, superimposed from outside. For Stahl motion derives from the anima. It is in no sense material (this, indeed, follows clearly from the concept that motion is not a property of matter). On the contrary, he considers it to be immaterial. Motion, then, is somehow reified into an immaterial entity representative of the anima, which is also immaterial. The immaterial anima acts through motion-also immaterial—and in turn affects material particles.

This sequence is Stahl’s answer to the problem, how can an immaterial entity act on something material. This difficulty, the crux of Cartesian dualism, had remained a stumbling block. One popular “solution,” widely accepted, involved an intermediary— the animal spirits, which were extremely subtle matter. The soul acted on the animal spirits, which, being material, could then act on the coarser material elements. This formulation employs a sort of Neoplatonic maneuver whereby extremely subtle matter seems to mediate the transition between the conceptual realm and the material world.

This “solution,” however, simply begs the question. Stahl, by calling motion an immaterial entity subject to control through the anima. believed that he had solved the problem. The concept of motion served as a link whereby an immaterial anima could act on the body.

The most important motions of the body are primarily the circulation of the blood. and then those motions that activate the processes of excretion and secretion. Without these, life could not exist. Motion, operative on the humors and the solids, maintains life and health. If the motions are impaired, disease occurs, Motion. Stahl emphasized, is not life but merely its instrument. This concept of instrumentality has extreme importance for his system, which centered on the anima.

We do not perceive the anima, nor can we study it directly. Instead, we perceive and study the bodily activities in health and the changes in disease, that is, physiology and pathology, and from these data we infer the nature of the anima. Stahl was not in any sense an obscurantist or mystic but, rather, a hard-headed clinician. He taught that the proper study of medicine involves the functions of the body, and his voluminous writings concerned themselves with physiology, pathology, and clinical medicine. But while emphasizing the importance of these aspects, he placed them in a suitable perspective: that the motions of the body, in health and in disease, are subordinate to a certain directing and integrating force–the anima.

The mind acts on the body in various ways. So-called voluntary actions, depending on a deliberate exercise of will, are quite obvious. But more important for Stahl’s system are those bodily effects that result from other psychic causes. Stahl repeatedly referred to the effects on the body produced by psychic disturbance, and he offered examples in two major areas. What we today call emotions–anger, fear, disgust, hatred, love –produce certain significant changes in the bodily functions. The alterations in pulse, respiration, or various digestive activities that result from emotional stress were well-known and obviously were quite different from “voluntary” motions that involve skeletal muscle. Stahl’s reasoned explanation presupposed an immaterial ens, the anima, that felt the emotion and reacted on the bodily organs by inducing changes in their motion.

In a second major illustration, used repeatedly, Stahl fell back on the belief that in a pregnant woman the emotions of the mother exert a material effect on the body of the fetus. It was a firm article of belief that a mother could “mark” the baby in utero. In emotional states such as fright or desire, the psychic state could have a physical effect upon the baby. Stahl could not explain in detail how this came about: but he did use these examples to bolster his claims that the anima, of immaterial psychic character, had power over the body.

The physical effects of emotion provide merely a striking example of a general situation; that primary changes in the mind are, through motion transferred to the solids and fluids of the body. But this is merely a special case. Actually, according to Stahl, the anima affects the body at all times. It is continually exerting regulatory and directing functions over all bodily activities —and these functions are all purposive.

This is the crux of animism. The anima regulates all bodily actions in accordance with certain goals. Life is purposeful. The anima is the source not merely of motion but also of directive, purposeful motion. Purpose thus involves the deliberate activity of mind, whereas chance concerns the activity of matter alone, without the intervention of mind. Purpose, implying a goal toward which activity is directed, has what we may call a forward reference, comparable with the final cause of Aristotle. Whatever happens by chance depends solely on backward reference, the vis a tergo.

Around these ideas Stahl constructed his important distinction between mechanism and organism. Mechanical properties depend only on the configuration, size, position, and movement (or disposition to movement) of the component parts. The movements have purely mechanical causes. In an organism, however, movements are combined toward a specific end, with a responsible agent that regulates and integrates them. To be sure, in any organism the activities involve mechanism, but merely in an instrumental fashion, subordinate to the purpose, goal, or intent constitutes the reason for existence of the organism. A mechanism does not have such a reason for existence.

Stahl provides numerous examples. In a watch, for instance, a skillfully constructed mechanism, the parts act on each other in mechanical fashion. But the watch also has properties of an organism, insofar as it has the goal of keeping time. If, because of defective parts, it fails to keep correct time, it no longer has the properties of an organism but remains a mere mechanism.

In entities that are not man-made, the question of possible goal or purpose lies beyond human knowledge. Thus, no one can penetrate the ends served by celestial bodies or the existence of so many species of insects. The answers can lie only in the will of God.

The anima Stahl made explicitly clear, exists only in the body, is inseparable from it, and cannot be thought of apart from the body. It is not a religious concept, nor is it an obscurantist or mystical doctrine. It is understood by rational analysis, which discloses that the anima is entirely dependent upon the body for perception and ideas. The body is the instrument of the anima, which must have sensory organs to aid the intellect and locomotive organs to aid the will.

Stahl rejected the view that bodily action is carried out solely by the motion of particles. The mechanical philosophy, depending on the vis a tergo, simply did not explain observed phenomena. For example, a certain noise—a stimulus falling on the ear —may induce a turning of the eyes toward the noise. Mechanists explained this by the activity of certain particles of the body, incited by the sense organs and reaching the motor organs to act upon them directly and to induce movement. In contrast, Stahl gave the example of a miser who hears a noise like a falling coin. He not only turns his eyes (what we would call a simple reflex) but also searches the entire room, with all the complicated associated movements. He does not stop until he finds the object of his search. That such complex behavior should have a simple mechanical explanation in the motion of particles seemed utterly absurd to Stahl.

Stahl propounded some views that may also seem absurd unless we relate them to the Aristotelian background and see the relationship between the anima of Stahl and the form of Aristotle (especially as the Aristotelian doctrine is manifest in the sixteenth- and seventeenth-century Galenits). Stahl declared that the body exists only because of the anima, and its form structure are determined through the energy of the mind. More important, there must reside in the anima some special knowledge of the organs, knowledge that regulates growth, shape, and function, and keeps the organs in proper proportion and relationship— proper, that is, for undertaking their functions and achieving appropriate goals. This concept of the immaterial entity controlling both growth and other activity ties in with the Galenists’ notion of “substantial form.” The form of the oak inheres in the acorn and determines its development into an oak rather than into a pine or a dahlia. Because of an appropriate form, the seed of a radish develops into a radish and not into a chrysanthemum. Stahl’s anima includes among its many other functions the directive activities that earlier writers had attributed to form.

Stahl met one obvious objection head on. The anima is a conscious agent, but many of the activities attributed to it do not appear in consciousness. We are, for example, consciously aware of sensations but not of directing the growth of bodily parts. Stahl disposed of this objection through a verbal distinction. He distinguished logos from logismos, ratio from ratiocinatio. Logos is simple “intelligence” or “perception” which cannot be the subject of reasoning or memory and can inhere in the anima without being perceived. This is quite different from ideas, which, derived from the external senses, serve as the subject of reasoning and memory (logismos Stahl was saying that the soul has ideas and activities of which it is not fully aware.

All this, of course, merely begs the question; but it does maintain the empirical analysis. At work are forces the nature of which can be identified through observation. Stahl drew into a single concept all the forces operative in living organisms and bestowed on this aggregate the name anima.

In carrying out a particular activity, the anima must regulate all actions necessary to achieve that goal, even those performed unconsciously. Stahl gave the example that in jumping over a ditch, one controls various muscular movements without any awareness of doing so. Although conscious only of the final goal, the anima regulates all the activities needed to achieve that end. Similar considerations apply to the efforts of the anima in combating disease. For carrying out the proper end—the restoration of health—it performs all functions necessary for the task and for this goal calls into action various mechanical activities. The anima, in brief, is an intelligent agent that wills certain ends and therefore must have organs suitable for achieving them. The human body is the organ of the rational anima and is formed for its needs.

The goals of medicine are intensely practical: to maintain health, to keep the body free from threatening ailments, and to combat disease. To achieve these goals, practical medicine must rely on established experience, assisted by sound reason. Speculations that deflect medicine from its goal, even if buttressed by skillful arguments and experiments, have no use. Stahl emphasized that many aspects of knowledge are of little or no positive help. For example, he denied the value of detailed anatomical or chemical studies because attention to precise anatomical findings draws attention away from the body as a whole. And, as Stahl repeatedly indicated, medicine has to do with the whole living organism, presided over by the anima, rather than with specific actions of specific parts, which are only instruments. He also rejected from the confines of medicine the specific study of chemistry. Although one of the leading chemists of his era, he expressly denied that chemistry was advantageous in the theory or practice of medicine.

In his strictures Stahl was referring specifically to the teaching of the iatrochemists, who explained bodily activity by the use of a small number of concepts —acidity and alkalinity, coagulation and liquefaction, fermentation, volatility, acrimony. He cogently pointed out that a wide range of ailments was being attributed to essentially the same causes, and that the explanations had neither a priori support from assured theory nor confirmation in solid a posteriori experience, such as a concrete demonstration of fermentation or acidity. This type of doctrine he condemned as useless, unscientific, and sterile. The humors in health or disease simply did not show the various chemical changes that were being invoked as explanatory principles.

We need not concern ourselves with specific details of Stahl’s physiology or pathology. He stated that free and orderly circulation, secretion. and excretion are necessary in maintaining health. Harmful material must be eliminated, and if refractory to direct elimination, it must be converted into a state suitable for elimination. The basic reactions of the body exemplify the healing power of nature, through which the anima, as an intelligent active force, conserves life and restores health. If nature falters, the physician must use appropriate means to aid the natural processes.

In chemistry as in biology, Stahl strongly disavowed the mechanical viewpoint, which in turn opposed the qualitative philosophy of Aristotle. Aristotelian elements, four in number, embodied qualitative properties that served as the “principles” for material objects. In the mechanical philosophy, on the other hand, the particulate elements had quantitative attributes—size and shape, position and motion —while qualities and properties depended on the interaction of atoms. All atoms obeyed the laws of mechanics; but those that were round, for example, would react differently from those that were pointed or angular.

In addition to the Aristotelian and corpuscular philosophies, a third and more specifically chemical tradition with three principles (salt, sulfur, and mercury) had developed. These principles had a rather ambiguous status, for they represented not only certain qualities or predictable modes of behavior—such as hardness, inflammability, or volatility— but also concrete material substances. This ambiguity— being characteristic objects and at the same time representing properties that, by inhering in many discrete objects, explained the phenomena of change —went unresolved. Nevertheless, the spagyric elements helped to provide an essentially chemical mode of explanation.

Stahl realized that the simple mechanical atomist viewpoint could not adequately explain the phenomena in chemical operations. He was also aware that the atomist viewpoint must be not totally rejected but merely regarded as inadequate. Matter is not infinitely divisible but exists in elementary particles that are indivisible and impenetrable. Simple elementary bodies, however, are not found in isolation. Everything that we observe is composite, and these composites exist in a hierarchy of increasing complexity. Atoms, never existing by themselves, join to form simple molecules. These in turn unite into more complex molecules, to produce visible objects.

Correlative to this aspect of Stahl’s philosophy was the need to explain properties or qualities. In order to account for observed phenomena, the atoms must have specific reactive and qualitative characteristics. Stahl’s atoms do indeed bestow particular qualities on the various compounds. However, precisely how a particular quality or functional property relates to the size and shape of atoms he could not satisfactorily explain.

In his attempts to find adequate explanations, Stahl relied heavily on the doctrines of Becher, who believed in three elementary principles— air, water, and earth. Air, however, did not enter into combinations, so that water and earth formed the material bases of objects. “Earth,” however was not a unitary principle. It comprehended three different types: the first, having to do with substantiality. rendered bodies solid and vitrifiable; the second, of moist oily character, provided color, odour and combustibility: the third supplied weight ductility, and volatility. These three kinds of earth, despite denials, have rather obvious relationship to the spagyric salt, sulfur, and mercury.

Stahl adopted these views from Becher and used the name “phlogiston” to designate the second earth—the principle of combustibility. It differed from the other two earths, for the first and third could not be separated from the bodies in which they existed, whereas phlogiston did not form any such stable compound.

While the concept of three kinds of earth applied to the vegetable and animal kingdoms as well as to the mineral, the experimental bases for phlogiston rested principally on the behavior of minerals and metals. Striking evidence arose from the reversible relationship of metals and their calxes. A metal contained all three kinds of earth. When the metal was heated intensely, the phlogiston was driven off and a calx appeared. However, when phlogiston was reintroduced into the calx, the metallic form reappeared. Here we have a reversible process: calx plus phlogiston yields the metal; the metal minus phlogiston yields the calxes. When phlogiston was driven from a substance, the properties of that substance changed very markedly. And, similarly, if a substance lacking phlogiston received this element through appropriate chemical manipulation, the properties would change. This process also applied to nonmetallic minerals. Sulfur, for example, which had lent its name to the spagyric terminology, was deemed a compound consisting of vitolic acid plus phlogiston. Far from being synonymous with sulfur, phlogiston was merely a constituent of it.

For minerals the expulsion or reception of phlogiston was a reversible process, but this was not the case in the animal or vegetable kingdoms. Plants were particularly rich in phlogiston: but once it was driven out, the original compound could not be reestablished.

Phlogiston was an element or substance and not an abstract quality or property. As a substance it combined with other chemical substances to form compounds. But, unlike other elements, which could not exist in isolated form, phlogiston could exist in relatively pure form. Finely divided carbon or lampblack, obtained, for example, by holding a cold object close to burning turpentine, was relatively pure phlogiston, visible and palpable. But ordinarily the phlogiston was not directly perceptible. From its combined form it was set free and passed into the air. Flame was considered the whirling motion produced by the escape of phlogiston, and air was necessary for the production of this motion. The air did not enter into the compound but was the receptacle for the phlogiston. In the absence of air, phlogiston could not escape and consequently combustion could not occur. This provided a reasonable explanation for the observation that calcination could not take place in a closed vessel.

Stahl recognized the close relationship between phlogiston and air. Where the quantity of air was limited, the amount of combustion was correlatively limited. He explained this phenomenon through the postulate that air could absorb only a limited amount of phlogiston; and when the limit had been reached, no more combustion—no more liberation of phlogiston—could take place. What happened to the phlogiston that was poured into the air? The Stahlian chemistry held a theory of recycling-the phlogiston in the air passed into plants and thence could pass into animal bodies through the ingestion of plant material.

A retrospective analysis can point out innumerable flaws in the phlogiston theory; and the way in which later eighteenth-century chemists quite demolished the theory forms an important chapter in the history of science and of thought. But this should not blind us to its important role as a bridge between the older concepts and the new. It tried to modify an existing intellectual framework in order to explain experimental observations. It succeeded, but only at the expense of ignoring certain other observations. And it proved unable to encompass new observations as scientific ingenuity devised new experiments.

BIBLIOGRAPHY

Stahl was a very prolific writer, and his doctrines form the subject of a vast secondary literature. Only a few of the more important writings can be mentioned here.

I. Original Works. Three relatively short essays provide a background for Stahl’s general medical philosophy. Disquisitio de mechanismi et organismi diversitate (Halle, 1706); Paraenesis, ad aliena a medica doctrine arcendum (Halle, 1706); and De vera diversitate corporis mixti et vivi (Halle, 1707). His greatest single medical work is Theoria medica vera, physiologiam et pathologiam. . . sistens (Halle, 1708), which provides in quite massive detail his doctrines of physiology and pathology, and presents his animistic philosophy as incidental to the exposition. The work includes, as intrinsic introductory material, the three essays mentioned above, plus a fourth, Vindiciae & indicia de scriptis suis. A further ed. of the Theoria medica vera was published at Halle in 1737. A more recent, 3-vol. ed. edited by Ludovicus Choulant was published at Leipzig in 1831-1833. The work has never been translated into English.

A French rendition of Stahl’s writings, Oeuvres médico-philosophiques et pratiques, translated with commentaries by T. Blondin, II-VI (Paris, 1859- 1864), apparently was intended as 6 vols. , although vol. I was not published. This ed. is, unfortunately, rare. The translation is fairly good, although sometimes quite verbose and excessively interpretive.

A German text expounding Stahl’s doctrines is Karl Wilhelm Ideler, Georg Ernst Stahl’s Theorie der HeilKunde, 3 vols. (Berlin, (831–1832). Although often referred to as a translation, it is only an abbreviated paraphrase. At best it can serve as a “finder” — a rapid way of getting an overview and of locating significant passages that must then he studied in the original Latin.

Stahl and his pupils published extensive clinical studies, describing particular problems, that are significant for the light they throw on the medical practice of the times—for instance. Collegium casuale magnum (Leipzig, 1733)— but these are not especially relevant here. He also wrote or was coauthor of a considerable number of dissertations, many of which are available at the National Library of Medicine, Bethesda, Md., and are important for any definitive study of Stahl.

A further work that deserves special mention is Negotium otiosum seu σκiαεαχiα(Halle. 1720). an attempt to answer some objections that Leibniz had made to Stahl’s animistic doctrines.

Stahl’s more specific chemical writings are very numerous. Partington, II 659–662, has devoted almost four pages to the bibliographic listing, taken from an eighteenth-century bibliography prepared by J. C. Goetz.

One of the earliest is Zymotechnia fundamentalis (Halle. 1697). Other important works are Specimen Beccherianum appended to Stahl’s ed, of Becher’s Physica subterranea (leipzig. 1703): and Zufällige Gedancken. . . über den streit von den sogenannten Suplhure (Halle, 1718). which was translated into french by Holbach as Traité du soufre (Paris, 1766). Fundamenta chymiae dogmaticae et experimentalis (Nuremberg. 1723), prepared by Stahl’s pupils, was translated by Peter Shaw as phylosophical Principles of Universal Chemistry (London, 1730). fundamenta chymiae dogmatico-rationalis g experimentails( Nuremberg. 1732) had a 2nd ed. In 1746. Another important work that presents Stahl’s doctrines was written by his pupil Johann Juncker: Conspectus chemiae theoretico practicae (Halle,1730)

II. Secondary Literature. Only a few of the more significant secondary sources can be listed. A relatively recent work is Bernward Josef Gottlieb. “Bedeutung und Auswirkungen des Hallischen Professors. . . Georg Ernst Stahl auf den Vitalismus des XVIII Jahrhunderts, insbesondere auf die Schule von Montpellicr,” in Nova acta Leopoldina, n.s. 12 , no. 89 (1943). 423–502. which covers a great amount of literature but does not exhibit any specially penetrating insight and is far too concerned with Teutonic chauvinism. Walter Pagel, “Helmont, Leibniz, Stahl,” in Archiv für Geschichte der medizin24 (1931), 19–59, is an important contribution. Albert Lemoine. Le vitalisme de l’animisme de Stahl (Paris, 1864) is an important nineteenth-century analysis: an older but very helpful discussion is under the heading “Stahlianisme.” Dictionnaire des sciences Médicales, 60 vols. (Paris, 1812–1822), LII, 401–449. Every general history of medicine devotes space to Stahl. Of especial value, and a source for many subsequent but more shallow discussions, is Kurt sprengel Versuch einer pragmatischen Geschichte der Arzneikunde 2nd ed.. V (Halle. 1803), 9–47. Stahl’s animism especially in relation to Friedrich Hoffmann’s mechanistic views, is discussed in two recent articles by Lester S.king: “Stahl and Hoffmann: A Study in Eighteenth Century Animism,” in Journal of the History of Medicine, 19 (1964). 118–130; and “Basic Concepts of Early Eighteenth Century Animism,” in American Journal of the psychiatry124 (1967), 797–807

A very important secondary source dealing with Stahl’s chemistry is J. R. Partington, History of chemistry (London. 1961). 637–690. An indispensable analysis of the chemical doctrines is Héléne Metzger, Newton Stahl, Boerhaave et la doctrine chimique ( Paris, 1930).

Lester S. King

STAHL, GEORG ERNST

(b. Ansbach, Germany, 20 October 1659; d. Berlin, 14 May 1734), chemistry, animism, vitalism, combustion, alchemy, medicine. For original article on Stahl see DSB, vol. 12.

Stahl has a prominent place in the histories of both chemistry and medicine, and had a successful career in court service and medical practice. His attempt to account for the inflammability of matter and reduction of metals was developed in the eighteenth century by his followers into a phlogistic paradigm preceding the modern chemistry of combustion that Antoine-Laurent Lavoisier (1743–1794) and his colleagues established. His medicine stressed the fundamental difference between the organism and the machine, and was thus opposed to a medical orientation of his time that sought to reduce medicine into mere mechanics and hydraulics of body parts and fluids.

Much new work has been done or come to light since the publication of Lester S. King’s biography of Stahl in the original DSB. Stahl’s year of birth, long held by historians as 1660, was found to be 1659 based on a birth certificate found in his parents’ parish church in Ansbach. His formulation of life has been under rigorous analysis by philosophers and historians alike. There have been fine studies on his relationship with the Pietsts in Weimar and Halle. And very importantly, scholars have come to a better understanding of Stahl’s chemistry, matter theory, and alchemy, subjects that King neglected to a large degree in his biography.

Career and Life Stahl was born into a Lutheran family in Ansbach, Germany in 1659. His father Johann Lorenz, an MA, worked in different times as a secretary to the council of the court (Hofrat) of Brandenburg-Ansbach, the Lutheran church consistory, and the local marriage court; his mother Maria Sophia Meelführer was the daughter of a local deacon. He went to the local gymnasium and thereafter studied medicine at Jena, then a stronghold of chemical medicine. Stahl received his MD at Jena in 1684, and taught there as an unsalaried lecturer until he began in 1687 to serve as personal physician (Leibmedicus) to the Duke of Saxon-Weimar. In 1694 he accepted the offer of the professorship of medicine at the newly opened University of Halle. He and Friedrich Hoffmann (1660–1742), also a Jena MD and an advocate of mecha

nistic medicine, soon made their faculty one of the most flourishing in Germany, although they before long developed an intense rivalry. Also on the faculty upon the inauguration of Halle were Christian Thomasius (1655–1728), famous jurist representative of the Early Enlightenment in Germany; August Hermann Francke (1663– 1727), theologian and leader of German Pietism; and Johann Franz Buddeus (1667–1729), professor of moral philosopher and Lutheran theologian. Christian Wolff (1679–1754) joined the faculty later, in 1706.

Although he thrived as a professor of medicine, Stahl also enjoyed a distinguished career as a clinician and a courtier. He practiced medicine from the time that he received his MD, if not earlier, and renewed his courtier career when he was called in 1715 to serve as first physician to King Friedrich Wilhelm I of Prussia (r. 1713–1740). Compared with Hoffmann’s dismissal from the same position in 1712 after a mere three years, Stahl’s continual service at court in Berlin until his death was a significant success, and doubtless it was owed to the king’s trust in his medical care. His fame as a clinician transcended national borders so that the ailing Russian Tsar Peter the Great tried twice to invite him to his sickbed in St. Petersburg. Besides attending to the health of the king and his family, Stahl was a court councilor (Hofrat) and was entrusted with the presidency of the medical board that regulated issues related to medicine, pharmacy, and public health in Berlin and later over all of Prussia. He was also instrumental in the founding of a college of medicine and surgery (inferior to the university in status) in Berlin in 1724.

Scientific Work in Chemistry Stahl’s chemical work demonstrates the width and depth of his knowledge of chemical practitioners’ work, as well as of his own empirical observations and experimentations. His first book, Zymotehnia Fundamentalis (1697), showed his acquaintance with brewers’ and bakers’ practical knowledge of fermentation. His works on metallurgy, inflammable materials, and salts recorded his familiarity with miners’ and smelters’ practice and beliefs and with chemical literature, in addition to his rich observations on minerals and often elaborate laboratory experiments.

Stahl had a corpuscularian, and largely mechanistic, interpretation of matter and chemical processes. Though agnostic about the number of the most fundamental particles, which he at times identified as indivisible atoms, he postulated that natural substances resulted from the aggregation or compounding (mixtio) of composite corpuscles of different orders. Chemical processes were the recombinations of the constituent corpuscles of starting materials. Because the primary qualities of the fundamental particles were unknown, Stahl proposed to examine the changes of physical and chemical qualities at the phenomenal level. He nevertheless was certain that particles were by nature passive, and their motion was transported by other particles in motion and ultimately came from heat. His rather mechanistic interpretation of fermentation, basically as the release of sulphurous particles in the fermentable materials, quietly rejected the theories of fermentation prevalent prior to his time that stressed the ferment as a somewhat magic agent that accounted for material changes in all the three kingdoms of animal, vegetable, and mineral. It also left no room for the Aristotelian form in the explanation of material constitution and changes.

Stahl himself did not seem to see phlogiston as his invention. Following Johann Joachim Becher (1635– 1682), he denoted the substance underlying all inflammable matters with the term phlogiston, although the roots of this notion can be traced at least back to the Paracelsian notion of sulphur as the principle of inflammability. This trace is evident in Stahl’s regular references to inflammable or oily substances as sulphurs and his frequent substitution of “phlogiston” with Schwefelswesen (essence of sulphur or sulphurous being). What distinguished his Schwefelswesen from the previous Paracelsian principle of sulphur was its material identity. The Paracelsian principle worked like the Aristotelian element to the extent that it showed no material consistency in the different substances of which it was said to form a part. Robert Boyle especially ridiculed this material inconsistency of the Paracelsian principle and Aristotelian element in his Sceptical Chymist. As Boyle’s criticism was absorbed by the following generations, Stahl postulated, and tried to demonstrate, that the material composition of phlogiston remained uniform in all bodies that contained it, even though it did not exist in nature as a pure uncompounded substance. Phlogiston could be released into the air from inflamed sulphurous minerals, from vegetable substances in fermentation, or from animal parts in putrefaction. It could come into the corporeal constitution of animals by their digestion of vegetables, or into the vegetable constitution by the absorption of the air. Thus phlogiston circulated across the three kingdoms of nature and around the globe in air streams. It was nutrition for plants, especially for resinous trees. It reduced calxes into their metallic forms, restoring their luster, tinkling sound, and fusibility; when losing their phlogiston, metals were reversed into calxes. Thus phlogiston played a key part in the reduction of metals.

Conception of Vital Principle Stahl’s conception of material constitution dictated his theory of life. He observed that organic bodies decomposed almost immediately when deprived of life, and reasoned that the strong corruptibility of organic matter resulted from its chemical nature. He thus postulated that there must be a reason or a vital principle that kept the living body from its natural decomposition, and that this reason of life could only derive from something other than matter. Meanwhile the delicacy and complexity of life seemed to require that this vital principle worked with alacrity, precision, and spontaneity in response to the organism’s real-time needs to maintain health and ward off threats. Thus Stahl assumed that this principle must be an immaterial agent, which he sometimes called natura (nature), and sometimes anima(the soul). Galen and his early modern followers in medicine also taught that each organ had its natural “reason” so that it knew to perform its natural faculty at the right time, in the right way, and under the right circumstance. For Stahl, this spiritual agent, anima, usually exercised natural reason (ratio) in the conservation of the body or its parts, rather than performed the logical reasoning (ratio-cinatio) of the rational soul (often identified as animus by Stahl and his contemporaries). Because anima guided and regulated physiological processes in the living body, once misled, by emotions, for example, it produced illnesses. In this sense it became a pathological agent. The participation of anima in physiology and pathology in accordance with reason and the purpose of life thus made the living organism distinct from a machine made of dead material parts. Medicine, the science of life, therefore must never be a mere application of mechanical principles.

Such a formulation of life ascribed much to the healing power of nature, a doctrine that dates back at least to the Hippocratic authors. For Stahl, the fact that very often the organism healed itself without resorting to medicine served as a proof of natura or anima at work, employing natural measures such as fever, hemorrhages, vomiting and diarrhea when necessary. The aim of the physician’s therapeutics was to facilitate this natural healing power based on attentive observation. Reckless interventions or crude applications of mechanical principles would cause disastrous effects.

It must not be thought that Stahl ignored the importance of mechanism in medicine. The material body was an indispensable instrument of the soul, and its operation basically followed mechanical principles. He assigned a great place to what he called tonic motion (motus tonicus), a contractive and relaxative movement of body parts or tissues. In his theoretical formulation that took almost a decade to complete, the contraction and relaxation of the tissues regulated the passage of the circulatory blood, and, thanks to the porous structure of the tissues, filtered out waste and harmful particles in the capillary blood flow into excretive ducts, thus playing as a key devise of metabolism. All these functions of tonic motion were achieved through corporeal mechanisms, although, as always, anima as the agent directed the motion.

Critique of Alchemy Stahl was an interested investigator of alchemy in the first few decades of his career but later turned into a critic. He examined as a believer the theories and experiments on the philosopher’s stone in the first chemistry course he taught in 1684, and still wrote approvingly, though also cautiously, on transmutation in the 1700s. In works published in the late 1710s and 1720s, he came to criticize Becher’s alchemical belief and the general Renaissance alchemical assumptions, although he retained his allegiance to Becher’s theory of material composition. In his well-known “Bedancken von der Gold-macherey,” he distinguished between chemistry (chemie) and alchemy (alchemie), seeing the former as useful, practical work as opposed to the latter as fruitless, and often fraudulent, effort.

A deeper significance of Stahl’s criticism is his departure from the vitalist cosmography that the alchemy of Becher and many Renaissance authors relied on. Renaissance vitalism often assumed an animating principle that originated in the heavens and permeated the celestial and terrestrial space alike, or a vital principle that was immanent to the most fundamental unit of matter, the monad or semina. In contrast, Stahl’s formulation of life and matter deprived organic substance of any form in the Aristotelian sense, of the animal and vital spirits in Galenic medicine, and of the cosmic spirits or immanent seminal principles. This formulation broke with the unity of heaven and earth, and of life and matter in Renaissance vitalism, and came to emphasize the difference between the living organism and dead matter, and indeed between the bio-medical and the physico-chemical.

It is often suggested that Stahl’s medicine had a natural bond with Pietism. It is true that Stahl had a long relationship with the Pietists, which began at least at the court of Saxon-Weimar, ran through his tenure at Halle, and continued even at court in Berlin. He was on good terms with Francke and served a king who, though Calvinist himself, was a patron of the Pietists. Some of Stahl’s students either played important parts in the pharmacy of the Weisenhaus (as Fracncke’s institution of charities was known) or became devout Pietists. Yet these relations were not enough to confirm that Stahl’s sympathy with Pietism shaped his medicine or that Pietism was by nature opposed to mechanistic medicine. Stahl’s rival, the mechanist Hoffmann, for example, befriended and was befriended by the Halle Pietists, and also supported some programs of the Weisenhaus. Robert Boyle, probably the best-known mechanical philosopher, was held in high regard by the Pietists. Although Stahl shared with the Pietists’ criticism of excessive mechanistic reductionism, it must be remembered that Boyle and Hoffmann, as good Christians, were careful to avoid the danger of atheist materialism. By contrast, Stahl’s physiology, pathology, and therapeutics showed few elements that were distinctly characteristic of Pietism (spiritual rebirth, for example), or that proposed religious causation of illnesses (such as the effects of sin on health).

Influence The influence of Stahl’s medical and chemical teachings was enormous over Europe throughout the eighteenth century. His students Johann Juncker (1679– 1759) and Michael Alberti (1682–1757) carried on his chemical and medical teachings at Halle. Alberti especially incorporated Pietist ideas into his medicine. Stahl’s emphasis on the irreducibility of biomedical phenomena to mechanical laws inspired the doctrines of the so-called Montpellier vitalists, including François Boissier de la Croix de Sauvages, Théophile de Bordeu (1722–1776), and Paul-Joseph Barthez (1734–1806), although the eighteenth-century vitalists, finding it increasingly difficult to defend the place of anima in medicine for theoretical and empirical reasons, later differentiated themselves, “the vitalists,” from Stahl, “the animist.” Although Albrecht von Haller, perhaps the most influential medical figure in mid-century Germany, was critical of Stahl, eminent late eighteenth-century figures in life sciences such as Johann Friedrich Blumenbach (1752–1840) and Pierre Jean Georges Cabanis (1757–1808) hailed him as a genius in medicine. Stahl’s chemistry was introduced to Paris largely thanks to Guillaume François Rouelle (1703–1770), and found among his followers Pierre-Joseph Macquer (1718– 1784) and Gabriel-François Venel (1723–1775). His teaching of phlogiston was developed in the 1780s and 1790s into a theory of combustion that tried to incorporate new findings in pneumatic chemistry by Joseph Black (1728–1799), Joseph Priestley (1733–1804), Henry Cavendish (1731–1810), Carl Wilhelm Scheele (1742– 1786), and others. Stahl’s formulation of tonic motion is discernible in the discussion of tonic motion in the lectures of John Thomson (1756–1846) published as late as 1813.

SUPPLEMENTARY BIBLIOGRAPHY

Stahl published most of his works in Latin, the academic language of his age, prior to 1715, the year of his departure for Berlin. Then gradually his works were translated into German, and in the 1720s especially, his dissertations were translated in large numbers. Stahl supervised more than a hundred and forty dissertations, and wrote a great majority of them on his students’ behalf. In Halle he experimented with new forms of publication of his age: for example, a personal periodical, Observationes physico-chymico-medicae curiosae (monthly from July 1697 to June 1698, apparently imitating his colleague Thomasius’ well-known precedence Monatsgespräche ), and a learned journal, Observationvm selectarvm ad rem litterariam spectantivm (1700–1705), co-edited with Thomasius and Buddeus. In Berlin he began to write and publish directly in German, which met with the new trend of learned German chemico-medical authors’ publication practice.

WORKS BY STAHL

Dissertatio epistolica ad Tit. Dominum Johannem Adrianum Slevogt … De motu tonico vitali, & hinc inde pendente motu sanguinis particulari. Jenae, Germany: Sumtibus Joh. Jacob Ehrten, 1692. The first of Stahl’s publications on tonic motion.

Zymotechnia fundamentalis, seu Fermentationis theoria generalis … Halle, Germany: Typis & sumptibus Christoph. Salfeldii, 1697. A theory of fermentation, where Stahl’s matter theory was first laid out.

Propempticon inaugurale de differentia rationis et ratiocinationis… Halle, Germany: 1701. A dissertation program on the difference between natural reason (ratio) and logical, reflective thinking (ratiocinatio).

Dissertatio medica inauguralis de vita. Halae Magdeburgicae: Typis Johannis Jacobi Krebsii, 1701. One of Stahl’s first treatises that formulated what life was.”

Specimen Beccherianum …” In Physica Subterranea by Johann Joachim Becher. Lipsiae: Apud Joh. Ludov. Gleditschium, 1703. Stahl republished Becher’s work in order to append this commentary.

Opusculum chymico-physico-medicum curiosorum. Halae Magdeburgicae: Typis & Impensis Orphanotrophei, 1715. A collection of Stahl’s early works, including Zymotechnia Fundamentalis and articles published in his personal periodical and in the journal Observationvm selectarvm.

G. E. Stahls zufällige Gedancken und nützliche Bedencken über den Streit von dem so genannten Svlphvre … Halle, Germany: In Verlegung des Wäysenhauses, 1718. Stahl’s study on inflammable bodies and their material base.

Georgii Ernesti Stahlii Negotium otiosum, seu, Skiamachia: adversus positiones aliquas fundamentales, theoriae verae medicae à viro quodam celeberrimo intentata… Halae: Litteris et Impensis Orphanotrophei, 1720. A collection of the polemic epistolary exchanges between Stahl and Leibniz on the nature of life.

Herrn George Ernst Stahls, … Chymia rationalis et experimentalis: oder, gründliche, der Natur und Vernunfft gemässe und mit Experimenten erwiesene Einleitung zur Chymie … Leipzig, Germany: bey Caspar Jacob Eysseln, 1720. A chemical textbook based on the notes of his lectures given in 1684. It was translated into English by Peter Shaw as Philosophical Principles of Universal Chemistry … (London: Printed for J. Osborn and T. Longman, 1730), which is one of the very few works by Stahl available in English.

Ausführliche Betrachtung und zulänglicher Beweiss von den Saltzen … Halle, Germany: In Verlegung des Wäysenhauses, 1723. A treatise on salts.

Billig Bedencken, Erinnerung und Erläuterung uber D. J. Bechers Natur-Kündigung der Metallen. Frankfurt & Leipzig, Germany: W. C. Multz, 1723. A commentary of Becher’s Natur-Kündigung der Metallen (1661), in which Stahl criticized alchemical theories and beliefs on the nature of metals.

Ausfürliche Abhandlung von den Zufällen und Kranckheiten des Frauenzimmers. Leipzig, Germany: C. J. Eysseln, 1724. A collection of Stahl’s gynecological dissertations, translated into German.

“Gedancken von der Gold-Macherey.” In Johann Joachim Becher, Chymischer Glücks-Hafen, oder, Grosse Chymische Concordantz und Collection … Halle, Germany: Verlegts Ernst Gottlieb Krug, 1726. Stahl’s relatively well-known critique of alchemy.

Praxis Stahliana, das ist … Collegium practicum … Leipzig, Germany: Eyssel, 1728. A collection of Stahl’s medical cases.

OTHER SOURCES

Chang, Ku-ming (Kevin). “Fermentation, Phlogiston, and Matter Theory: Chemistry and Natural Philosophy in Georg Ernst Stahl’s Zymotechnia Fundamentalis.” Early Science and Medicine 7 (2002): 31–64. An analysis of Stahl’s largely mechanistic matter theory that places his formulation of fermentation in the intellectual context of his age and his own conceptual development.

———. “The Matter of Life: Georg Ernst Stahl and the Reconceptualizations of Matter, Body, and Life in Early Modern Europe.” PhD diss., University of Chicago, 2002.

———. “Motus Tonicus: Georg Ernst Stahl’s Formulation of Tonic Motion and Early Modern Medical Thought.” Bulletin of the History of Medicine 78 (2004): 767–803. An analysis of the formulation and development of Stahl’s theory of tonic motion.

———. “Georg Ernst Stahl’s Alchemical Publications: Anachronism, Reading Market, and a Scientific Lineage Redefined.” In New Narratives in Eighteenth-CenturyChemistry: Contributions from the First Francis Bacon Workshop 21-23 April 2005, 23-43. Dordrecht: Springer, 2007.

———. “From Vitalistic Cosmos to Materialistic World: The Lineage of Johann Joachim Becher and Georg Ernst Stahl and the Shift of Early Modern Chymical Cosmology” In Chymists and Chymistry: Studies in the History of Alchemy and Early Modern Chemistry, edited by Lawrence M. Principe, 215-225. Segamore Beach, MA: Science History Publications, 2007.

Coleby, L. J. M. “Studies in the Chemical Work of Stahl.” PhD diss., University College, University of London, 1938. A very good study of Stahl’s chemistry, unfortunately never published, and thus very rare.

De Ceglia, Francesco Paolo. Introduzione alla fisiologia di Georg Ernst Stahl. Lecce: Pensa, 2000. A survey of Stahl’s physiology.

———. “The Blood, the Worm, the Moon, the Witch: Epilepsy in Georg Ernst Stahl’s Pathological Architecture.” Perspectives on Science 12 (2004): 1–28. A study of Stahl’s conception of epilepsy and pathology in general.

Duchesneau, François. “G. E. Stahl: Antimécanisme et Physiologie.” Archives internationale d’histoire des sciences 26 (1976): 3–26. Duchesneau, a philosopher and an intellectual historian, analyzes Stahl’s medical thought with philosophical rigor.

———. “Leibniz et Stahl: divergences sur le concept d’organisme.” Studia Leibnitiana 27 (1995): 185–212.

———. “Stahl, Leibniz, and the Territories of Soul and Body.” In Psyche and Soma: Physicians and Metaphysicians on the Mind-Body Problem from Antiquity to Enlightenment, edited by John P. Wright and Paul Potter. Oxford: Clarendon Press, 2000.

Engelhardt, Dietrich von, and Alfred Gierer, eds. Georg Ernst Stahl (1659–1734) in wissenschaftshistorischer Sicht: Leopoldina-Meeting am 29. und 30. Oktober 1998 in Halle (S.). Halle (Saale): Deutsche Akademie der Naturforscher Leopoldina, 2000. The proceedings of a conference on Stahl.

Geyer-Kordesch, Johanna. “Georg Ernst Stahl’s Radical Pietist Medicine and its Influence on the German Enlightenment.” In The Medical Enlightenment of the Eighteenth Century, edited by Andrew Cunningham and Roger French. Cambridge, U.K.: Cambridge University Press, 1990. A very influential article that suggests Stahl’s strong ties to the Pietists.

———. Pietismus, Medizin und Aufklärung in Preussen im 18. Jahrhundert: das Leben und Werk Georg Ernst Stahls. Tübingen: Niemeyer, 2000. A fundamental work that elucidates the Pietist background for Stahl’s life and work. Includes an updated, though selective, bibliography, of works by and on Stahl, limited to his medical works.

Goetze, Johann Christoph. Scripta D. Georg. Ern. Stahlii …, aliorumque ad ejus mentem disserentium, serie chronologica … Norimbergae: Apud Petr. Conr. Monath, 1726. A contemporary, annotated bibliography of Stahl’s publications, albeit not complete.

Helm, Jürgen. “Das Medizinkonzept Georg Ernst Stahls und seine Rezeption im Halleschen Pietismus und in der Zeit der Romantik.” Berichte zur Wissenschaftsgeschichte 23 (2000): 167–190. A study of the reception of Stahl’s influence in Halle Pietism and German Romanticism.

———. “‘Quod naturae ipsae sint morborum medicatrices.’ Der Hippokratismus Georg Ernst Stahls.” Medizinhistorisches Journal 35 (2000): 251–262.

———. Krankheit, Bekehrung und Reform: Medizin und Krankenfürsorge im Halleschen Pietismus. Habilitationschrift, Universität Halle-Wittenberg, 2004. A section of this fine work reconsiders the place of Pietism in Stahl’s medicine work.

Hoffmann, Paul. “La controverse entre Leibniz et Stahl sur la nature de l’âme.” Studies on Voltaire and the Eighteenth Century 199 (1981), 237-49.

———. “L’âme et les passions dans la philosophie medicale de Georg-Ernst Stahl.” Dix-Huitiènme Siècle 23 (1991): 31–43.

Metzger, Hélène. “La Philosophie de la matière chez Stahl et ses disciples.” Isis 8 (1926): 427–464.

———. “La théorie de la composition des sels et la théorie de la combustion.” Isis 9 (1927): 294–325. These two outstanding articles form the basis of the part on Stahl in her Newton, Stahl, Boerhaave et la doctrine chimique (Paris: Alcan, 1930).

Partington, J. R., and Douglas McKie. “Historical Studies on the Phlogiston Theory.” Annals of Science 2 (1937): 361–404; 3 (1938): 1–58, 337–371. A series of papers that traces the development and fall of the phlogiston theory in the works of the late eighteenth-century pneumatic chemists.

Rather, Lelland J. “G. E. Stahl’s Psychological Physiology.” Bulletin of the History of Medicine 35 (1961), 37–49.

Rather, Lelland J., and John B. Frerichs. “The Leibniz-Stahl Controversy—I: Leibniz’ Opening Objections to the Theoria Medica Vera.” & “The Leibniz-Stahl Controversy—II: Stahl’s Survey of the Principal Points of Doubts.” Clio Medica 3 (1968): 21–40; 5 (1970): 53–67. An English translation of part of the polemics between Stahl and Leibniz, with a concise analysis.

Strube, Irene. Georg Ernst Stahl. Leipzig, Germany: B. G. Teubner, 1984. A book that is based on her dissertation, “Der Beitrag Georg Ernst Stahls, 1659–1734: zur Entwicklung der Chemie,” University of Leipzig, 1961. It is in her dissertation that Stahl’s birth certificate was first presented, and it corrected the received knowledge of the year of his birth.

Völker, Arina, and Wolfram Kaiser, eds. Georg Ernst Stahl (1659–1734): Hallesches Symposium 1984. Halle (Saale): Martin-Luther-Universität Halle-Wittenberg, 1985. The proceedings of a conference held in the 250th anniversary of Stahl’s death.

Völker, Arina. “Bei Durchsicht der Stahlschen Disputatioslisten.” In Georg Ernst Stahl, edited by Arina Völker and Wolfram Kaiser. Halle (Saale): Martin-Luther-Universität Halle-Wittenberg, 1985. A list of Stahl’s dissertations. It does not include the prefaces (called programs or propempticons) he wrote for a selected number of the dissertations. These dissertations and programs are very important for understanding Stahl’s medical teaching.

Ku-Ming (Kevin) Chang

Georg Ernst Stahl

The German chemist and medical theorist Georg Ernst Stahl (1660-1734) was the founder of the phlogiston theory of combustion and the author of a theory of medicine based upon vitalistic ideas.

Georg Stahl was born on Oct. 21, 1660, at Anspach in Bavaria, the son of a Lutheran pastor. Although brought up in an extremely pious and religious household, he early showed an enthusiasm for chemistry. By the age of 15 he had mastered a set of university lecture notes on the subject as well as a difficult treatise by Johann Kunckel.

Stahl studied medicine at the University of Jena, where he graduated in 1683. Here he came under the influence of iatrochemical theories, which gave an interpretation of physiological processes in terms of chemistry. He was later to become a strong opponent of this school of medical theory. Following graduation he taught at the University of Jena for 10 years.

In 1694 Stahl was invited to fill the second chair of medicine at the newly founded University of Halle. He owed his appointment to the recommendation of the holder of the first chair of medicine, Friedrich Hoffmann. They made Halle one of the most important medical schools of the early 18th century, although their careers there were punctuated by frequent quarrels. For 22 years Stahl lectured at Halle and wrote an impressive list of works on chemistry and medicine. His lectures were said to have been dry and intentionally difficult; he is alleged to have had a low opinion of the intellectual capacity of his students at Halle.

Stahl's most notable contribution to chemistry was his famous phlogiston theory of combustion, which became one of the main unifying theories of 18th-century chemistry. He maintained that all substances which burned contained a combustible principle called phlogiston (from the Greek phlogos, a flame) which was liberated during the combustion process. This principle of phlogiston was present not only in such obviously combustible substances as wood, wax, oils, and other organic materials but also in inorganic substances such as sulfur and phosphorus and even in metals. Thus when a metal was calcined by heating (a process now known as oxidation), the metal was said to lose its phlogiston. Conversely, when the metallic calx was reduced again to the metal, phlogiston was taken up.

This theory also offered the first explanation of why charcoal was used in the smelting of metallic ores. Charcoal was a substance rich in phlogiston (since on burning it left no residue), and in the smelting process the phlogiston passed from the charcoal to the ore to give the pure metal. One of the major achievements of this theory was that it offered a comprehensive explanation of so many seemingly disparate chemical phenomena. In developing his theory, Stahl drew from the earlier ideas on combustion of the late-17th-century German chemist J.J. Becher.

As a medical theorist, Stahl opposed the purely chemical and mechanistic explanations of living phenomena current in his time. He emphasized the gulf between living and nonliving materials, stating that the distinctive feature of the former was that they possessed a soul which prevented their decomposition. His reintroduction of animistic or vitalistic ideas into physiology had great influence on 18th-century medical theory.

Stahl retired from academic life in 1716 to take up appointment as physician to King Frederick I of Prussia. He held this post until his death on May 14, 1734.

Further Reading

There is no major study of Stahl's life in English, but for his contributions to chemistry see John M. Stillman, The Story of Alchemy and Early Chemistry (1960); and James R. Partington, A History of Chemistry, vol. 2 (1961). □

Georg Ernst Stahl

1660-1734

German chemist and physician remembered for developing phlogiston theory—combustion and calcination consist of phlogiston loss. Stahl postulated that ash from burnt wood and calx from heated metals are devoid of phlogiston, and heating calx with phlogiston-rich charcoal yields metal by calx re-absorbing phlogiston. Accounting for observed weight changes required phlogiston to have negative weight. Though incorrect, Stahl's theory greatly facilitated the shift from alchemy to Antoine Lavoisier's new chemistry. Within medical thought, Stahl's vitalism provided an alternative to Hermann Boerhaave's mechanist theories.

Georg Ernst Stahl

1659?-1734

German chemist and physician who is best remembered as one of the main developers of the phlogiston theory of combustion, which dominated the chemical sciences for a hundred years. Stahl studied medicine at the University of Jena, and later lectured there. He became the court physician at Weimar, then professor of medicine at the University of Halle, and eventually served as personal physician to the King of Prussia. Stahl also produced influential medical writings and founded a short-lived chemical journal.