The "four humors" is an ancient medical concept that suggests human health and temperament are influenced by four bodily fluids: blood, phlegm, yellow bile, and black bile. Each humor is associated with specific personality traits and physical conditions. For example, an excess of blood is thought to make a person cheerful and sociable, while too much black bile may lead to melancholy. This theory originated in ancient Greece and was popularized by the physician Hippocrates. It influenced medical practices for centuries, suggesting that imbalances in these humors could lead to illness. Although modern medicine has moved beyond this concept, it remains a significant part of historical medical understanding.