Mesmer refers to Franz Anton Mesmer, an 18th-century physician from Germany. He is best known for developing a theory called "animal magnetism," which suggested that an invisible fluid in the body could be manipulated to heal ailments. Mesmer believed that this fluid could be influenced through magnetic forces, leading to a state of trance or heightened suggestibility in patients. His practices laid the groundwork for modern hypnosis and psychotherapy. Although his ideas were controversial and often criticized, they sparked interest in the mind-body connection and the potential for psychological healing. Today, hypnosis is recognized as a legitimate therapeutic technique, partly due to Mesmer's early contributions.