Franz Anton Mesmer, born in 1734 near Lake Constance, studied medicine in Vienna and in 1766 wrote a dissertation on the influence of the planets on the human body that scholars say was largely lifted from Richard Mead’s 1704 work. Marriage to the wealthy widow Anna Maria von Posch made him a patron of Viennese society, and legend has him hosting the premiere of 12-year-old Mozart’s Bastien und Bastienne in his garden. In 1774 he and astronomer Maximilian Hell treated Franziska Osterlin with iron and magnets, and when her symptoms eased, Mesmer concluded the healing force came from him. He called it animal magnetism.

In 1775 he explained away the exorcist Johann Joseph Gassner’s cures as natural magnetism, a moment historian Henri Ellenberger links to the birth of dynamic psychiatry. The failed treatment of blind pianist Maria Theresia Paradis drove him from Vienna to Paris in 1778, where his group sessions became a sensation. In 1784 King Louis XVI appointed a commission including Benjamin Franklin, Antoine Lavoisier and Joseph-Ignace Guillotin to test his claims.

• His idea of illness as blocked flow and the crisis of shaking and convulsions he tried to provoke
• The baquet, an oak tub of iron filings and bent iron rods with patients roped together around it
• A mocking scene in Mozart’s Cosi fan tutte and the glass harmonica music played during treatments
• Blindfold tests, Lavoisier’s water cups and a boy collapsing at a supposedly magnetized tree in Franklin’s garden
• How the Marquis de Puysegur continued the trance work and James Braid named it hypnotism in 1843