Humorism, or humoralism, is a now discredited theory of the makeup and workings of the human body, adopted by Greek and Roman physicians and philosophers, positing that an excess or deficiency of any of four distinct bodily fluids in a person directly influences their temperament and health. From Hippocrates onward, the humoral theory was adopted by Greek, Roman and Islamic physicians, and became the most commonly held view of the human body among European physicians until the advent of modern medical research in the nineteenth century.