Clare Coffey at The New Atlantis:
Mesmerism is the brainchild of Franz Mesmer, a German doctor born in 1734 who practiced medicine in Vienna and Paris, and who believed in the influence of magnetic fluids and astronomical movements on human physiology. (If that sounds particularly quaint, consider that today Dave Asprey has built an empire offering advice such as that walking barefoot is a necessary and healing method of getting in touch with the earth’s electrical energy.)
The doctor regularly treated his patients with magnets, and one day, while employing his technique on a female patient, he discerned a fluid in her body that responded to his manipulations. Mesmer called the fluid “animal magnetism,” a term that in general use now means raw charisma. As he used it, “animal” just meant “vital”; it was the force that sustains and animates us. When it became blocked or flowed in the wrong direction, physical and mental ailments resulted. In this, mesmerism resembled Reiki, developed in Japan by Mikao Usui about a hundred years later. But unlike Usui, who claimed to regulate intangible, spiritual energies, Mesmer claimed to have made a bona fide breakthrough in physiology. He presented himself as a scientist, not a healer.