In the 1770s, the theory of "animal magnetism" (or mesmerism) was established by the German physician Franz Anton Mesmer. Animal magnetism gained traction in the former half of the 19th century as the study developed and gained a greater foundation in science. In a time when numerous physiological questions were being raised, mesmerism offered an explanation and a solution to abnormal human psychology and behavior. 

Mesmerism posited that there existed in living things a force, or a magnetic fluid, that could be harnessed by an operator and used either to heal or control an individual. The inherent metaphysical basis of mesmerism called into question its reliability as a science, and it was widely contested by the English medical community. Its pushback was magnified by its foreign origin. Studies of mesmerism were most widely practiced in France and Germany, so its presence in England magnified revolutionary anxieties.