Four Humors Theory

The Four Humors Theory, originating in ancient Greece, suggests that human health and temperament are influenced by four bodily fluids: blood, phlegm, yellow bile, and black bile. Each humor was believed to correspond to specific qualities—blood (sanguine) was linked to optimism, phlegm (phlegmatic) to calmness, yellow bile (choleric) to anger, and black bile (melancholic) to sadness. Imbalances among these humors were thought to cause illness and emotional states. Although this theory has been largely replaced by modern medicine, it played a significant role in shaping early understandings of health and personality.