Franz Anton Mesmer

Franz Anton Mesmer was an 18th-century German physician whose 1766 medical dissertation on planetary influence on the human body matured into the doctrine of “animal magnetism”—the claim that a single, invisible, fluid-like force pervades the universe and that imbalances in its flow within the body produce disease.

Practicing first in Vienna and, after professional scandal, in pre-Revolutionary Paris, Mesmer treated patients by directing this supposed fluid through magnetized objects, hand passes, and group sessions around his famous baquet, frequently inducing dramatic convulsive “crises” he interpreted as the fluid breaking through blockages.

His 1779 Memoir on the Discovery of Animal Magnetism gave the theory its programmatic statement. Mesmer’s historical significance lies less in the truth of his theory—a 1784 French royal commission including Benjamin Franklin and Antoine Lavoisier concluded the effects were caused by “imagination,” not any physical fluid—than in the transition he unwittingly began.

By insisting that an operator could systematically alter another person’s bodily and mental state, he created the practical laboratory from which the psychology of suggestion would emerge. Where he framed reality-manipulation as the control of an occult cosmic current, his successors progressively relocated that power into the mind itself.

Mesmer is therefore the indispensable first hinge in the long shift from mystical fluids to psychological suggestion, even though he himself never abandoned the fluid hypothesis.