What are the four humors?

Hippocratic Oath Read more from
Chapter Medicine and Disease

The four humors are the bodily fluids: blood, phlegm, yellow bile, and black bile, originating in the heart, brain, liver, and spleen, respectively. One work assigned to Greek physician Hippocrates (c. 460-c. 377 B.C.), Nature of Man, asserts that illness is caused by an imbalance of the four humors (fluids) in the body. The presence of these humors was thought to determine the health and personality of a person. This belief prevailed for centuries but was finally discredited by modern science.

During the Middle Ages (500–1350) each of the humors was assigned certain characteristics. Someone of ruddy complexion was believed to have an excessive amount of blood in his or her system; that person would be sanguine (cheerful and optimistic) in character. (The word sanguine is derived from the Latin word sanguiss, meaning “blood.”) Someone who had an imbalance resulting in more phlegm was considered phlegmatic, and would have a slow and impassive temperament. An individual who had excessive yellow bile was considered hot-tempered. And a person who had more black bile in his or her physiological system was believed to be melancholic.


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