We are often totally unaware of where the words we use come from — even, or especially, words we use all the time. The prime examples of this are dead metaphors. Before the horrors of the Marne and the Somme in World War I, for example, nobody spoke of someone who wouldn’t budge as being “entrenched” or of “retrenchment.” Now “retrenchment” is a piece of jargon in IT business strategy, as well as in foreign policy and military affairs.

The deadest of metaphors have no known origin, and there are more of them than most people notice. Think of just the words that evoke our breathing: When we are “inspired,” we are filled up with breath or with air. But “inspiration” has long since ceased to be understood as a metaphor for inhalation. We speak of “a stroke of inspiration” as a cliche, though it makes no sense for a breath in to stroke. “Respire,” the combination of inspiration and expiration, is something we think of as referring to breathing. But when is the last time you thought of expiration as something you do with your lungs? That metaphor is totally dead, expired. Kind of makes you think differently about when the time on the meter expires, doesn’t it? Don’t let your parked car suffocate.