humours

Humours, in ancient and medieval medicine, refer to a theory that the human body contains four humours whose balance determines health and temperament. The concept originated in ancient Greek medicine and was elaborated by Galen; it guided medical thinking in Europe and the Middle East for centuries.

The four humours are blood, phlegm, yellow bile, and black bile. Blood is associated with the air and a sanguine temperament—warm and moist; phlegm with water and a phlegmatic temperament—cool and moist; yellow bile with fire and a choleric temperament—warm and dry; black bile with earth and a melancholic temperament—cold and dry. Health was thought to exist when these fluids were in proper balance; disease or mood shifts were seen as an excess or deficiency of one fluid.

To restore balance, physicians used diet, exercise, medications, and procedures such as bloodletting and purging. Seasonal and environmental factors were believed to influence humour balance. The theory informed diagnostics, prognosis, and treatment until advances in anatomy and physiology in the 17th century and later reduced its authority.

In modern times the four-humour theory is regarded as obsolete, but it shaped early medical thought and language. Terms such as melancholic or sanguine reflect the historic linkage of temperament to bodily fluids. The concept also influenced literature, art, and social understandings of health and personality, and remains a historical example of how medical frameworks shape culture.