Franz Anton Mesmer, the creator of animal magnetism, reacted by insisting on the physical nature of his treatments when Benjamin Franklin and other people asserted that animal magnetism does not exist. At first, Mesmer attributed his treatments to electric or magnetic forces. He later gave up on these explanations, opting instead for a theory based on a "universal fluid" that had an impact on the nervous system. All living things possess a fluid known as "animal magnetism," according to Mesmer, and it can be used to treat illnesses. Franklin disapproved of animal magnetism, but Mesmer persisted in defending his methods and the success of his treatments.