Dr Anton Mesmer believed in the power of “animal magnetism”, as a universal force that could cure illness. His patients would gather around a large enclosed wooden tub with iron wands protruding out of it. The patients would hold the wands and touch them to their afflicted parts. Mesmer indicated that the animal magnetism would flow from the tub through the wands to the patient. Patients often went into hysterics and thought they were cured. Mesmer became well known in the upper echelon in Paris and attracted the attention of King Louis XVI. The Parisian medical establishment was not pleased to see many of their highest paying patients leaving them to seek the excitement of Mesmer’s salon. Thus, the King appointed a Royal Commission to study Mesmer’s theory.

The King chose the best scientific minds of the day to examine Mesmerism. Benjamin Franklin was chosen as chair the committee. Other well-respected members included Jean Bailly (1736–1793), an astronomer; Antoine de Jussieu, a botanist; Antoine Lavoisier, a famous chemist; Joseph Guillotine, an all-around scientist.

The Commissioners first learned all about the process before setting out to test the theory of animal magnetism. Mesmer described animal magnetism as “a fluid universally diffused, the vehicle of a mutual influence between the celestial bodies, the earth and the bodies of animated beings”. Mesmer’s animal magnetism cannot be seen, so the Commission had to find unique ways of measuring it. In an empty treatment salon the Commissioners put an electrometer and compass next to the mesmeric tub and found nothing. The Commissioners also underwent treatment themselves, separate from the crowds, but not one of the Commissioners felt any sensation.

They then conducted experiments based on the logic of Mesmerism. they performed a series of ingenious experiments to determine to what degree the power of the imagination can influence sensation and to demonstrate whether imagination can be the cause in whole (or could it interact with magnetisim to create the effect).

One experiment involved magnetizing a tree and determining whether a susceptible person would be affected by touching it. The person was brought before many trees with his eyes covered, and asked to embrace them. Each tree affected him and before he got to the fourth tree he fainted. Unfortunately, for mesmerism none of those trees had been mesmerized.

In another experiment a patient was seated next to a closed door and told that a magnetic operation was occurring right behind the door. The patient became hysterical, but there was actually nothing behind the door. Another patient was presented with several basins which she was falsely told had been magnetized. She became hysterical around these basins. When she drank from a basin that was magnetized, she drank from it calmly.

As a result of these blind trials, the Commissioners concluded that Mesmer’s universal fluid had no existence and that imagination, imitation, and touch were the true causes of the effects of mesmerism. Response to the Commission’s report was rapid and furious from the backer’s of mesmerism. One profesional mesmerizer published a book of letters written by patients claiming that therapy worked for them. Eventually, mesmerism declined and to my knowledge is no longer practiced (Note: Many of the Commisioners, such as Bailly and Lavoisier, as well as the King all suffered much more violent ends in the French Revolution).

Does the legacy of mesmerism still exist? Much of the field of hypnotism was founded by Armand Puysegur, a student of Mesmer. Hypnotism has been doubted in similar ways as mesmerism. EMDR (Eye Movement Desensitization and Reprocessing) has also been accused accused of being a pseudoscience. Scott Lilenfeld, a psychologist who often writes about pseudoscience says: “you can usually tell (what is pseudoscience) because there’s a lot of marketing around these treatments, but there’s no controlled evidence. Support consists of almost all anecdotes and personal testimony.”

The participant blind trials conducted by the Commission were ingenuous at the time. In my humble opinion, the spirit of scientifically solving a problem displayed by the Commission seems to be much more powerful than simply relying on rhetoric, bad science, and anecdotal evidence that is often used even today.

For a highly entertaining and well written article, please see this 1999 article from Richard McNally on the comparison between Mesmerism and EMDR.