For 2000 years, European medicine was based on the humoralism theory of Galen (129–216) and Hippocrates (460– 370 BCE). According to humoralism, the human body is filled with four basic liquids, called humors, which are in balance when a person is healthy.

All diseases and disabilities supposedly resulted from an excess or deficit of one of these four humors. Humoralism also claimed that temperament and health are determined by the ratio of the four bodily liquids. Deficits were thought to be caused by vapors inhaled or absorbed by the body.

The four humors are blood, phlegm, yellow bile and black bile.

This theory was based on Empedocles (490–430 BCE) theory of the four roots—fire, air, water, and earth. Earth is predominantly present in the black bile, fire in the yellow bile, water in the phlegm, and all four are present in the blood.

Health could be maintained or restored by balancing the humors, and also by regulating air, diet, exercise, sleep, evacuation and emotion. Medical treatment consisted of enemas, bleeding, emetics (cause vomiting), laxatives (ease defecation), purgatives (strong laxatives), and cathartics (accelerate defecation).

Phlebotomy, leeching, cupping, purges, and emetics were the primary medical interventions. This is the paradigm and terminology of catharsis to which Breuer was heir.

Galen’s humoralism was not displaced until 1858—by Rudolf Virchow’s theories of cellular pathology.