Take humoral theory: In the Middle Ages, the body was thought to consist of four liquid components called humors—blood, yellow bile, black bile, and phlegm.

A hot and dry person was thought to be choleric and ruled by yellow bile, associated with childhood and summer.

In a skeleton drawing of a galumphing, long-gone dodo, a litany of bodily and emotional states, including guilt and yellow bile, is interwoven with attempts to cope — witchcraft, too much sex, strong imagination and more.

The Greek physician Hippocrates believed that people’s personalities were governed by the amounts of phlegm, blood, black bile and yellow bile that flowed through their bodies.

The human body contained four viscous liquids or “humors”: phlegm, blood, yellow bile and black bile.