Humors

Humors, in historical medical theory, referred to the four bodily fluids whose balance was believed to determine health and temperament. The four humors are blood, phlegm, yellow bile (choler), and black bile (melancholy). According to humoral theory, illness results from an excess or deficiency of one or more humors, and remedies aimed to restore balance through diet, lifestyle, and specific medical interventions.

The concept originated with ancient Greek physicians and was refined by Galen, who linked each humor to particular qualities, seasons, and personality types. Sanguine, phlegmatic, choleric, and melancholic temperaments were thought to arise from different humoral mixtures. Diagnostic practices relied on clinical observation, including pulse, urine, skin tone, and other symptoms, to infer a humoral imbalance. Treatments included changes in diet and environment, exercise, and, in many cases, procedures such as purging, emetics, or bleeding to rebalance fluids.

Humoral theory shaped Western medicine for roughly a thousand years, influencing medical education, diagnosis, and therapy. It also contributed to broader cultural ideas about personality and behavior, linking physical state and mood. By the early modern period, advances in anatomy, physiology, and pathology, along with the rise of germ theory, undermined the validity of humoralism. The theory was gradually abandoned in favor of evidence-based explanations of disease.

Today, the term humors mainly survives in historical context and in idiom. The word humor also endures as a reference to mood or wit, while the ancient notion that bodily fluids govern health is considered obsolete in contemporary medicine.