The four humors of Hippocratic medicine are black bile (Gk. melan chole), yellow bile (Gk. chole), phlegm (Gk. phlegma), and blood (Gk. haima), and each corresponds to one of the traditional four temperaments. A humor is also referred to as a cambium (pl. cambia or cambiums).
Essentially, this theory holds that the human body was filled with four basic substances, called humors, which are in balance when a person is healthy. All diseases and disabilities supposedly resulted from an excess or deficit of one of these four humors. These deficits could be caused by vapors that were inhaled or absorbed by the body. The four humors were black bile, yellow bile, phlegm, and blood. Greeks and Romans, and the later Muslim and Western European medical establishments that adopted and adapted classical medical philosophy, believed that each of these humors would wax and wane in the body, depending on diet and activity. When a patient was suffering from a surplus or imbalance of one fluid, then said patients' personality and physical health would be affected. This theory was closely related to the theory of the four elements: earth, fire, water and air; earth predominantly present in the black bile, fire in the yellow bile, water in the phlegm, and all four elements present in the blood.
Paired qualities were associated with each humor and its season. The word humor is a translation of Greek χυμός, chymos (literally juice or