Monica told me that I made her night tonight. This is all because I introduced her to the term "hill of beans," as in, "That idea isn't worth a hill of beans." She had never heard the expression before. She asked me what it meant. I told her, but it got me thinking about something I recently learned of called the dead metaphor.
A dead metaphor is a metaphor that has been used so frequently that it is now an idiom, or figure of speech, but has been used for so long that no one knows what it originally referred to.
Take, for example, a phrase like "toe the line." Most people would probably write that phrase as "tow the line." This shows how disconnected we are from the original meaning. When a runner was about to begin a race, he would "toe the line." The line was the beginning mark for the race. Today, we use the expression to refer to conformity to a standard, much like the runner who set up as close as he could to the mark but no farther.
I'm curious to know where "it's raining cats and dogs" originated from.
Anyway, dead metaphors are quite interesting, and they begin to show up all over the place once the concept is pointed out. As far as Monica goes, it doesn't surprise me that she has never heard "a hill of beans." She had never heard of Garth Brooks either.