9. The Four Humors Govern Health
For over a thousand years, medicine was dominated by the theory of the four humors: blood, phlegm, yellow bile, and black bile. Ancient doctors believed that the balance of these fluids determined not only a person’s health but also their temperament and personality. Treatments like diet changes, purging, and bloodletting were designed to restore this elusive balance. The rise of modern medical science eventually replaced the humoral system, but its influence can still be seen in some medical language and ideas today. Explore more at History.com
