Galenism

Galenism, or Galenic medicine, is the medical doctrine associated with Claudius Galenus (c. 129–c. 200/216 CE). It shaped Western medical theory and practice for more than a millennium and formed the basis of medical education in medieval Europe and the Islamic world.

The central feature of Galenism is humorism: the body is governed by four humors—blood, phlegm, yellow bile, and black bile. Health consists in their balanced proportions, while disease reflects an excess or deficit of one or more humors. Treatments aim to restore balance through diet and climate, regimens of exercise, and sometimes physical interventions such as purging, cupping, or bleeding, along with pharmacological remedies.

Anatomy and physiology under Galen relied on animal dissection and inference. Galen proposed the concept of the circulatory system and a vascular physiology that linked the heart, vessels, and pneuma (breath) with bodily heat and temperament, though many specific claims were later shown to be incorrect.

Galen’s pharmacology categorized drugs as simples and compound remedies, with properties described in terms of hot, cold, moist, and dry. He also integrated medical theory with a theory of the four temperaments (sanguine, phlegmatic, choleric, melancholic) to explain individual differences in disease and response to treatment.

Legacy and critique: Galenism persisted through the medieval Islamic world (where scholars such as Avicenna and Rhazes built upon his work) and into European scholastic medicine until anatomical and experimental advances of the Renaissance and later undermined its authority. Today, Galenism is studied as a historical framework in the history of medicine and pharmacology.