Armand-Marie-Jacques de Chastenet, Marquis de Puységur (1751-1825), was a French aristocrat and military officer and an initiate of Mesmer's Société de l'Harmonie. In 1784 he carried the magnetic technique to his family estate at Buzancy, near Soissons, and there observed something Mesmer had not emphasized: magnetizing certain subjects produced not the violent 'crisis' of the Paris baquet but a calm, sleep-like state in which the subject was lucid, spoke, took direction, and afterwards remembered nothing. He named it artificial, or magnetic, somnambulism. His standing (an aristocratic officer with a country estate and a Mesmerian credential) and the gentler, less alarming character of his method gave the practice a respectability Mesmer's convulsive sessions had begun to lose. He set out the discovery in his 1784 *Détail des cures opérées à Buzancy*, expanded it in his *Mémoires pour servir à l'histoire et à l'établissement du magnétisme animal*, and gave it a mature physiological statement in the 1811 *Recherches* on somnambulism.
[2] EXCLUSIVE ACCESS
Access ran through the same subscription societies that structured Mesmer's practice. Mesmer's Société de l'Harmonie, founded in Paris in 1783, sold instruction in the magnetic 'secret' for an initiation of 100 louis, a sum that priced out everyone below the wealthy professional and aristocratic class. Puységur, himself an initiate, founded a provincial society on that model, the Société Harmonique des Amis Réunis at Strasbourg, in 1785, to train operators and propagate the somnambulist method. The societies were the gatekeeping mechanism: the technique was taught to paying, vetted members and practiced on others. Puységur's own estate work at Buzancy was a separate, charitable face of the same movement, conducted among his peasants and dependents rather than sold.
[3] VAGUE MECHANISM
The proposed cause was Mesmer's universal magnetic fluid, supposedly redirected by the operator's hands and will. Puységur's innovation was to shift attention from the fluid itself to the state it was said to produce. In magnetic somnambulism the entranced subject was held to gain a lucid faculty: to perceive the seat of disease in their own body and in others, to prescribe remedies, and to predict the illness's course. This was a surrogate at one remove. The fluid was never demonstrated, and the diagnostic faculty rested on the testimony of operators and their somnambulists. The visible product, the trance state, was real, but the explanation attached to it was speculative from the outset.
[4] FINANCIAL CONFLICT
The conflict here is structural rather than personal. Puységur was a man of independent means who did not run a fee-charging clinic, and the sources describe his Buzancy treatment as non-commercial. But the movement that carried his method monetized access: Mesmer's Société de l'Harmonie charged its 100-louis initiation, and the provincial societies, including Puységur's Strasbourg Société Harmonique des Amis Réunis (1785), reproduced that paid, members-only structure. Puységur was simultaneously the developer of the somnambulism doctrine, the author of its principal texts, and a credentialing authority for the Strasbourg network. The interest at stake was less Puységur's purse than the authority and membership of a closed society selling instruction in an unfalsifiable technique.
[5] DISCONFIRMATION / COLLAPSE
Disconfirmation came in two waves. In 1784, the year of Puységur's discovery, the royal commission headed by Benjamin Franklin (with Lavoisier, Bailly, Guillotin, and others) examined animal magnetism under blind and controlled conditions and concluded that there was no magnetic fluid and that the effects followed the patient's imagination and expectation. That verdict struck the mechanism common to Mesmer and Puységur alike. The specific claims of magnetic somnambulism were tested later: when the Académie Royale de Médecine investigated somnambulists in 1826-1831, the Husson report allowed that magnetizing could induce sleep and altered sensibility but did not confirm any clairvoyant diagnosis, and the Burdin prize of 1837, offered for a somnambulist who could read with the eyes covered, was never claimed. The induced state survived as a real phenomenon and became part of the prehistory of hypnosis; the fluid and the clairvoyance did not.
OUTCOME
Magnetic somnambulism is the second act of animal magnetism: the form the practice took after the 1784 royal commission had emptied Mesmer's fluid of evidence. Puységur kept the fluid theory but moved the spectacle from the convulsive crisis to the lucid trance, and in doing so he made the practice quieter, more respectable, and more durable. The trance state he described was genuine, and once the magnetic fluid was discarded it became a direct ancestor of hypnosis and of the nineteenth-century study of suggestion. But the claims that gave the practice its therapeutic prestige, that a magnetic fluid acts on disease and that the somnambulist can diagnose by a lucid inner sense, did not survive controlled testing: the 1784 commission found no fluid, the Académie Royale de Médecine's commissions of 1826-1831 declined to confirm the diagnostic faculty, and the 1837 Burdin prize for eyeless reading went unawarded. The case is the same five-stage cycle as its parent, Mesmer's Paris practice, with the mechanism relocated from an apparatus to an induced mental state: a charismatic practitioner, access through paid societies, a surrogate dressed as a faculty, a closed credentialing interest, and eventual disconfirmation under controls.
FIGURES
FIG 1Subjects around the magnetized elm at Buzancy; the printed caption describes a patient entering 'somnambulisme parfait'. Plate from Puységur's Mémoires (Paris: J.G. Dentu, 1820). Wellcome Collection (Public Domain Mark). (1820)PUBLIC DOMAINsourceFIG 2A magnetizer inducing the magnetic state in a seated patient by passes of the hands. Wood engraving, ca. 1845. Wellcome Collection (Public Domain Mark). (1845)PUBLIC DOMAINsource
In 1784, the year the royal commission headed by Benjamin Franklin found no evidence for Mesmer’s magnetic fluid, one of Mesmer’s own initiates was producing a new version of the practice on his country estate. Armand-Marie-Jacques de Chastenet, Marquis de Puységur (1751-1825), magnetized the peasants and dependents at Buzancy, near Soissons, and found that some entered not the convulsive ‘crisis’ of Mesmer’s Paris baquet but a calm, sleep-like state in which they spoke lucidly, followed his direction, and woke with no memory of it. The first such subject was Victor Race, a young man on the estate. Puységur named the state artificial, or magnetic, somnambulism, and made it the centre of the practice: in this lucid sleep, he claimed, the subject could perceive the seat of disease and prescribe its cure.
The mechanism was still Mesmer’s universal magnetic fluid, supposedly redirected by the operator’s hands and will; at Buzancy, Puységur also magnetized a large elm on the village green and seated patients around it holding cords tied to the tree. Access to the technique ran through the subscription societies that had grown up around Mesmer: the Société de l’Harmonie in Paris charged 100 louis to teach the magnetic secret, and Puységur founded a provincial society on the same model, the Société Harmonique des Amis Réunis, at Strasbourg in 1785. Puységur himself was an aristocrat of independent means who did not run a fee-charging clinic, and his Buzancy work is recorded as charitable; the financial structure of the movement, paid initiation into a closed society, sat around him rather than in his own hands.
The disconfirmation came in two waves. The 1784 commission’s verdict (no fluid; effects from imagination, expectation, and suggestion) applied to Puységur’s practice as much as to Mesmer’s, since both rested on the same fluid. The distinctive claims of somnambulism were tested in their own right a generation later: the Académie Royale de Médecine’s commission of 1826-1831 (the Husson report) granted that magnetizing could induce sleep and altered sensibility but would not confirm the claimed clairvoyant diagnosis, and the Burdin prize of 1837, for a somnambulist who could read with the eyes covered, was never won. What remained was the trance itself, a real psychological state that the nineteenth century, having dropped the fluid, studied as suggestion and renamed hypnosis. The modern scholarly edition of Puységur’s memoirs is Adam Crabtree and Sarah Osei-Bonsu, The Marquis de Puységur, Artificial Somnambulism, and the Discovery of the Unconscious Mind (Routledge, 2024). The case is the direct successor of Mesmer’s (Mesmer 1778), the same structural cycle with its vague mechanism moved from the baquet to the patient’s own mind.
