Psychology Today | 04.06.2026 02:12
A common theme traceable back at least 2,000 years holds that neuropsychiatric illnesses are the result of an excess of substances (humors) within the body. Black bile was considered responsible for melancholia (depression); yellow bile produced a choleric explosive temperament; excess of blood led to a sanguineous confident disposition; and phlegm induced inactivity and passivity. This humeral theory was responsible for various diagnoses and treatments (like bloodletting) up until the mid-nineteenth century.
