Bloodletting is the practice of withdrawing blood from a patient to cure a disease. The practice was widely used in Antiquity and the Middle Ages. People stopped using it in the 19th century. The idea of bloodletting comes from an ancient system of medicine called Humorism: This system states, that there are different "humors" in the body. To remain healthy, a patient had to keep these humours in balance. Bloodletting was the most common medical practice performed by physicians from antiquity until the late 19th century, a span of almost 2,000 years.