Armand-Marie-Jacques de Chastenet, Marquis de Puységur

The Marquis de Puységur was a French aristocrat and army officer who became one of Mesmer’s most important disciples and, in 1784, made a discovery that quietly subverted his teacher’s entire system. While magnetizing a young peasant named Victor Race on his estate at Buzancy, Puységur found that instead of the expected convulsive “crisis,” Victor fell into a calm, sleep-like state in which he remained responsive—able to speak lucidly, follow instructions, and afterward remember nothing.

Puységur named this condition “artificial somnambulism,” and described it at length in his Memoirs on the Establishment of Animal Magnetism (1784). This finding marked a decisive conceptual mutation. Mesmer had located the curative power in the manipulation of a physical fluid; Puységur observed that the essential phenomenon was a special state of consciousness in the subject—one characterized by heightened rapport with the operator, apparent clairvoyance, and extreme suggestibility.

By attending to the subject’s altered mind rather than the operator’s fluid, Puységur shifted the locus of “reality-manipulation” inward, anticipating the psychological reframing that Braid and the Nancy School would complete.

He is the crucial second hinge in the transition from occult fluids to psychological suggestion: the man who first saw that the trance, not the magnet, was the real discovery.