Franz Antoine Mesmer and “Animal Magnetism” (2026)

Douglas J. Lanska

Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA

Correspondence: dlanska@wisc.edu

Keywords: Franz Antoine Mesmer; mesmerism; animal magnetism; Royal Commission; expectation

In the late eighteenth century, German physician Franz Anton Mesmer (1734–1815) described and promoted “animal magnetism” as a pervasive property of nature that could be used to cure various conditions (Lanska & Lanska, 2007, 2014). However, except for one notable disciple, and despite glowing testimonials from some patients, orthodox physicians, professional medical and scientific societies, and political bodies rejected him and his treatment and ultimately moved to terminate his practice.

Mesmer’s work started in Vienna in 1774, when Maximillian Hell, a Jesuit priest and the Austrian Astronomer Royal, introduced him to a new treatment using magnets applied to the body. When Mesmer applied Hell’s magnets to Franziska (“Franzl”) Österlin, a 28-year-old woman with “hysteria” (somatization disorder), her symptoms eventually disappeared albeit with some easily managed relapses. Afterward, Hell and Mesmer argued in public over credit and priority.

Mesmer soon dismissed Hell’s magnets as superfluous, because he could “magnetize” virtually any object and use it therapeutically. He “claimed to be able to fill bottles with this previously unrecognized magnetic material and direct it from a distance of 8–10 ft, even through other people or walls” (Lanska & Lanska, 2007, p. 303), to produce “jolts in any part of the patient that I wanted to, and with a pain as ardent as if one had hit her with a bar of iron” (Bloch, 1980, p. 28). To explain how this powerful force had escaped previous notice, Mesmer argued that such effects could not be perceived by healthy persons, but only by those in whom “the harmony is disturbed” (Bloch, 1980, p. 9).

Around 1775, Mesmer sent a summary of his ideas on animal magnetism to scientific academies across Europe and selected scientists (Bloch, 1980; Mesmer, 1779). Although most ignored him, the Berlin Academy replied dismissively, noting that: (1) Mesmer’s observations contradicted all previous experiments; (2) his supporting evidence for “animal magnetism” failed to prove its existence; (3) the absence of detectable effects in healthy persons made the existence of “animal magnetism” highly suspect; and (4) other explanations could account for the results (with strong suspicion that Mesmer had “fallen into the fallacy of considering certain things as causes which are not causes”) (Pattie, 1994, p. 46).

Mesmer attempted to demonstrate to physician-scientist Jan Ingenhousz the effects of animal magnetism in Miss Österlin (then in relapse) (Mesmer, 1779, 1781, 1948; Pattie, 1994). After Mesmer elicited convulsions by pointing a magnet toward her, Ingenhousz surreptitiously tested the effects of strong magnets he had concealed. Because she reacted only to objects that she believed were magnets held by Mesmer, and not to actual magnets hidden by Ingenhousz, he publicly denounced Mesmer as a fraud. Mesmer subsequently disparaged Ingenhousz’s scientific ability and pleaded for a court-ordered commission to establish the facts concerning his treatment. However, after Mesmer’s failure in the treatment of a second young woman, he was discredited and derided in Vienna and left for Paris in January 1778.

In Paris, Mesmer sought testimonials attesting to the value of his discovery from the Royal Academy of Sciences, the Royal Society of Medicine, and the Faculty of Medicine, but he was rebuffed or ignored. Mesmer’s attempt to demonstrate animal magnetism before a meeting of the Academy of Sciences in early 1778 failed to convince any of the attendees. Nevertheless, mesmerism became very popular in Parisian society, particularly his group treatments or séances around a baquet (vat) during which some patients experienced a convulsive “crisis.” The increasing popularity of mesmerism alarmed orthodox physicians and the monarchy, nobility, and police, who saw it and its secret societies as a threat.

Eventually, King Louis XVI established a Royal Commission to evaluate Mesmer’s claims. Commissioners included four physicians from the Faculty of Paris and five members of the Royal Academy of Sciences, including American polymath Benjamin Franklin and chemist Antoine-Laurent Lavoisier. A second commission was also established, drawn from the Royal Society of Medicine, but their report was largely redundant.

Commissioners conducted experiments to systematically isolate and independently vary explanatory factors (e.g., “magnetization,” expectation, and the person’s awareness of the body part magnetized), while holding other factors constant. Subjects developed characteristic mesmeric crises if and only if they expected to be magnetized, regardless of whether they were magnetized. The Commission concluded that the effects attributed to animal magnetism were primarily caused by the subjects’ own expectations of magnetization (“imagination”).

Publication of the Commission’s report eroded much of Mesmer’s support, greatly decreased his clientele, and helped shift popular opinion from support to scorn and ridicule (Franklin et al., 1784, 2002; Pattie, 1994). The Faculty of Medicine suppressed the professional practice of mesmerism (animal magnetism) by expelling any partisan members. Mesmer then left Paris and lived in relative obscurity.

Afterward, mesmerism was no longer a significant social event in Paris, but it persisted until around the middle of the 19th century across Europe and the United States as itinerant quacks used it to attract crowds (e.g., Twain, 2013, p. 297). More significantly, it influenced 19th-century developments in hypnotism, particularly the work of Scottish surgeon James Braid, who dismissed any influence of “animal magnetism” or external magnetic fluids, and argued that the hypnotic state was caused instead by internal neurophysiological mechanisms (Braid, 1843).

References

Bloch, G. J. (Ed.). (1980). Mesmerism: A translation of the original scientific and medical writings of F. A. Mesmer. William Kaufmann.

Braid, J. (1843). Neurypnology; or, The rationale of nervous sleep, considered in relation with animal magnetism. J. Churchill.

Franklin, B., Majault, [M. J.], Le Roy, [J.-B.], Sallin, [C.L.], Bailly, [J.-S.], d’Arcet, [J.], de Bory, [G.], Guillotin, [J.-I.], & Lavoisier, [A. L.]. (1784). Rapport des Commissaires chargés par le Roi, de l’examen du magnétisme animal [Report of the Commissioners appointed by the King to examine animal magnetism]. De L’imprimerie Royale.

Franklin, B., Majault, [M. J.], Le Roy, [J.-B.], Sallin, [C.L.], Bailly, [J.-S.], d’Arcet, [J.], de Bory, [G.], Guillotin, [J.-I.], & Lavoisier, [A. L.]. (2002). Report of the commissioners charged by the king with the examination of animal magnetism. International Journal of Clinical and Experimental Hypnosis, 50(4), 332–363. https://doi.org/10.1080/00207140208410109

Lanska, D. J., & Lanska, J. T. (2007). Franz Anton Mesmer and the rise and fall of animal magnetism: Dramatic cures, controversy, and ultimately a triumph for the scientific method. In H. Whitaker, C. U. M. Smith, & S. Finger (Eds.), Brain, mind, and medicine: Essays in eighteenth-century neuroscience (pp. 301-320). Springer. https://doi.org/10.1007/978-0-387-70967-3_22

Lanska, J. T., & Lanska, D. J. (2014). Franz Mesmer. In M. J. Aminoff & R. B. Daroff (Eds.), Encyclopedia of the neurological sciences, Vol. 2 (2nd ed., pp. 1106-1107).  Elsevier. https://doi.org/10.1016/B978-0-12-385157-4.00956-8

Mesmer, F. A. (1779). Mémoire sur la découverte du magnétisme animal [Memoir on the discovery of animal magnetism]. A Geneve.

Mesmer, F. A. (1781). Précis historique de faits relatifs au magnétism-animal jusques en avril 1781 [Historical account of facts relating to animal magnetism up to April 1781]. No publisher identified.

Mesmer, F. A. (1948). Mesmerism by Doctor Mesmer (1779). Being the first translation of Mesmer’s historic “Mémoire sur la découverte du Magnétisme Animal” (V. R. Myers, Trans.). Macdonald.

Pattie, F. A. (1994). Mesmer and animal magnetism: A chapter in the history of medicine. Edmonston.

Twain, M. [Clemens, S.] (2013). Autobiography of Mark Twain: The complete and authoritative edition, vol. 2. (B. Griffin & H. E. Smith, Eds.). University of California Press. https://doi.org/10.16995/la.1905