Animal Magnetism (aka Mesmerism)
Scientific thought could sometimes take strange turns when combined with cultural trends and beliefs. Animal magnetism was the late 18th-century brainchild of German physician Franz Anton Mesmer (1734-1815). He believed there was a universal "magnetic fluid" or force that could be found in, and have a physical effect on, all living things. By manipulating this fluid with magnets, one could manipulate the body into being well again — a universal cure for any disease.
Mesmer claimed that he could produce pain and jolts through walls or people, even at a distance, and was seemingly able to cure a wide variety of conditions with this one method. Due to his popularity, he expanded his methods to also include mass forms of treatment.
By the end of the century, mesmerism was mostly debunked and no longer popular in Europe. But experts conceded that even if it was the power of the patients' minds, these treatments were still able to cure conditions that had no other cure. They cautioned against using such treatment freely since the magnetizer or mesmerist could potentially do more harm than good.
Animal magnetism eventually saw a revival (as well as its fair share of deniers) in America during the late 19th and early 20th centuries. Today, we can trace concepts such as hypnotherapy to animal magnetism.
While its audience in Europe was mostly members of the upper class and the rich, mesmerism in America was more of a trend amongst the middle and working class. The use of gimmicks and stage hypnotism made it a more lowbrow entertainment and past-time than a medical treatment.
Yet the more American mesmerists dove into hypnotism and the hypnotic state, the more they had to think about the subconscious mind. Men like John Dods started to call animal magnetism "electrical psychology"; Phinease Parkhurst Quimby thought that it was people's beliefs and ideas that caused their own illnesses.
By identifying ideas and thoughts as the cause of American nervousness, as opposed to attributing them to magnetic fluids, Quimby made mesmerism something more akin to psychiatry.