Theory of the Four Humors

"I think there's a general misconception that anything written quickly lacks quality, and I don't believe that." 

-- Michael Connelly

By Alex P. Vidal

The celebrated Greek doctor Hippocrates postulated that all human emotions flowed from four bodily fluids, or humors: blood (which makes us cheerful and passionate), yellow bile (which makes us hot-tempered), black bile (which makes us depressed), and phlegm (which makes us sluggish or stoic).
Though the good doctor's humors have given behavioral scientists a nice structure for examining personality types (sanguine, choleric, melancholic, and phlegmatic), the idea that our bodily fluids makes us angry, depressed, or elated died out in the 1800s.

BELIEF

According to The Fascinating Book of History, the withering of the Hippocratic belief in humors proved to be good news for patients who were not thrilled with the practice of bloodletting, a process of opening a patient's veins to lower blood levels in an attempt to bring the humors into balance and cure all manner of mental and physical ills.

Bloodletting, with a knife or with leeches, was an accepted medical practice from the times of the Greeks, Mayans, and Mesopotamians.
It was going strong at the end of the 18th century, when George Washington had almost two liters of blood let out to cure a throat infection. He died shortly afterward.