When you’re feeling hopeful or optimistic about something you might say you’re feeling “sanguine” about it. If you’re like most people, you probably wouldn’t, but the point is that you could. “Sanguine” is a reasonably common word, although it doesn’t generally pop up in everyday conversation in most circles. But it has a pretty unusual history.
“Sanguine” entered English around the 1300s from the French word “sanguin,” which in turn was from the Latin “singuineus.” It originally meant “pertaining to blood.” Applied to a person, it could also mean either bloody or bloodthirsty. Those meanings have disappeared from the English “sanguine,” although there is the obscure adjective “sanguinary” that still means bloodthirsty or brutal. But how did “sanguine” evolve from meaning “bloody” to its current meaning of “optimistic”?
It all has to do with the way the human body was believed to function back in Medieval Europe (to be fair, the Europeans didn’t come up with these ridiculous theories on their own; they were based on ancient Greek and Roman delusions). The idea was that the body contained four substances called “humors.” Each one was associated with a particular mood, and true health was thought to be based on keeping the four substances in balance. The humors were “phlegm,” which made you calm and patient; “black bile,” which made you quiet, serious, or depressed if there was too much of it; “yellow bile,” which made you restless and when excessive, angry; and regular old blood, which for some reason made you hopeful and happy (here you’ll notice the eventual connection beginning to appear).
Although nobody believes in the humors system any more, the humors are still hanging around linguistically. There’s phlegmatic, which describes somebody who’s so calm they just take everything in stride, and there’s the somewhat archaic word bilious, which means you’re cranky — that word goes back to bile, specifically yellow bile. Another related word is melancholy, which today means sadness, and is based on the Greek word “melankholia”, which literally means “black bile.” And of course there’s sanguine, which means hopeful, and lo and behold is based on the old word having to do with blood.
The “humors” theory was finally dispatched in the 1800s when people began to have the idea that a better way to figure out how something worked was to actually study it carefully instead of sitting around arguing in the abstract. But in retrospect, it took a couple thousand years for people (who, evidence suggests, are not nearly as clever as they think they are) to figure out an idea that today seems perfectly obvious. So a Medieval critic of the humors theory (if there were any) might not have been sanguine about the idea of the humors system being replaced by something better any time soon.
