You may recognize the word phlegm, as in the bodily fluid, in our word of the day. It turns out there is a connection. So how did phlegm come to be associated with a synonym of ‘calm’ and ‘stoic?’ The answer goes back to the ancient Greeks. They believed that human personalities were controlled by four bodily fluids called humors: Blood, black bile, yellow bile and phlegm. Those ruled by phlegm were thought of as calm and unemotional. Centuries later, we would refer to such people as ‘the phlegmatic type.’