sanguine

Leaving T.H. White aside for the moment, I'm going back to my own often overly glib use of English after catching myself using the word "sanguine" a couple of times recently. It is not a word I would say, but it is apparently one I write without hesitation. I would never say "I am not overly sanguine about the prospect." I would say "I am not too confident about that." Or "I am not optimistic."
So why "sanguine"? Does it have a further (or, my fear, an entirely different)meaning than the more commonplace words? It sounds like it has something to do with blood. But perhaps not. Here goes:

Well, I am uncharacteristically close to the mark on this one. The word does mean cheerful or optimistic and it also means "of the color of blood" or red. The connection between the two lies in the medieval theory of the body as having four humors, or fluids--blood, phlegm, bile, and black bile. Charming. Anyway, one's personality was supposed to be controlled by one's dominant humor. If one was ruled by their blood, they were supposed to have a ruddy face and the qualities of courage, hope and the willingness to fall in love. Not too shabby. I hesitate to think what the qualities of one ruled by black bile were.

The dictionary notes that "sanguine" and "sanguinary" are related linguistically but very different in meaning. "Sanguinary" means bloodthirsty. I'd be willing to bet that most of the sanguinary types were, and probably still are, mainly the envious black bile people. Probably only hoping to put a few roses in their cheeks...