In his Dissertation, Mesmer defined animal magnetism as

the property, which bodies have of being susceptible to the action of a universally distributed fluid, a fluid which surrounds all that exists and which serves to maintain the equilibrium of all the vital functions.

The fluid is the substance animating all life—animal and vegetable:

This principle is of equal necessity to vegetation. It is because of this principle that the sappy juice is able to circulate, and thereby contribute to the plant’s development.

Eighteen years later, in his Catechism, Mesmer demoted the status of the physical magnets that he had been using to the status of metaphor. Animal magnetism was not a species of mineral magnetism:

Although this action, which is powerful in nature, has been given the name “magnetism,” the fluid which is the prime mover of this action does not appear to have the properties of the magnet. It does not behave as a magnet—a body, which is affected from the north to the south. On the contrary, the poles are vertical; that is to say, from bottom to top.

What, then, was the point of the magnets? And why use the term magnetism? Calling the therapeutic action magnetism while disavowing mineral magnetism is contradiction embraced for a good cause. Mesmer disowned the efficacy of mineral magnets in his theory but embraced their use in practice in order to enhance the placebo effect. To my knowledge this is the first self-conscious employment of placebos in the history of Western psychology.

In Buddhism such an approach is called skillful means—the employment of suboptimal bullshit in the service of helping the patient. The real placebo is the invisible magnetic force; real magnets are added for the sake of placeboic efficacy.

In fact, it is likely that he switched from “gravity” to “magnetism” precisely in order to enhance the placebo with empirically present props.

His group therapy sessions were astoundingly prop-rich. Real bathtubs filled with a witch’s brew of stuff (glass, metal, sand, water) which surely surged with the invisible fluid of life. This fluid then flowed through metal rods submerged in the brew and into the eagerly hopeful bodies of the patients. The life fluid traveled just like electrical fluid (which was in fact understood as a fluid at the time)—up the rods, across touching hands, and through fastened rope:

Tho the magnetizer could, so he said, mesmerize “dry,” even to charging bread, paper, wood, and jars and flasks with the wonderful fluid, the bottom of the “baquet” was eighteen inches deep in water. Its top was covered by a wooden lid, pierced with holes in which were jointed branches of iron for the patients to lay hold of. Around the “baquet” sat the patients with linked hands, and connected with a cord, ecstatically awaiting the fluid, from Mesmer’s magnetic fingers. Within the hall only a dim light penetrated the heavy curtains, and stillness reigned except that at intervals, soothing yet awe-inspiring notes of music floated up from below. Only Mesmer, arrayed in lilac satin and bearing a thin wand of iron, together with his assistants, Antoine and D’Eslon, moved about in the haunted gloom.

Dressed in easy, flowing robes, and handsome—for Mesmer thought no man useful who was not handsome—they walked to and fro, one of them occasionally stopping to fascinate some neurotic patient with his bright magnetic eye, or so holding the iron wand that a gush of the magnetic fluid passed into the fair one. Now and again Mesmer would put aside his wonder-working rod, and setting him self knee to knee and foot to foot, one hand on the patient’s stomach and one on her back, he would magnetize her who had taken his especial fancy.

For hours nothing would happen in particular, till, of a sudden, on one patient going off into hysterics or convulsions, the others would soon follow. This one would laugh and scream, that one hiccough and weep herself into a fit. Another would roll her eyes in a trance, while her neighbor was flinging herself about as if demented.

These elaborate theatrics were intended to give presence to what was absent—the animal fluid. He even had patients drink spiritually magnetize water enhanced with iron filings. It’s not mineral magnetic—he says so explicitly. And yet he uses magnets and magnetized metals … for their mineral-magnetic properties.

Mesmer was self-consciously practicing placebo therapy.

The takeaway seems to be something like …