From the time of Greco-Roman Medicine, the uncertain nature of hysterical illness was a fertile source of controversy. Because there were no testable objective signs of disease, the diverse ideas relating hysteria to the uterus and to psychological and physiological causes generated persisting polemics. Theories fluctuated chaotically, influenced by social changes of prosperity or deprivation, current attitudes, and issues of gender. Faced with a large number of patients with such illnesses as well as many with epilepsy, mental illnesses, and organic nervous disorders, Charcot set about investigating hysterics to determine what neurological abnormalities might explain them. His many predecessors, from Sydenham and Willis in the 17th century to Briquet and Bourneville in the 19th century, whose views are outlined in this chapter, both conditioned and influenced his efforts. Charcot succeeded in promoting his work at Salpêtrière, which for a time was respected throughout the world.