Why does “touchstone” mean what it does? And other words

Raining cats and dogsI’m fascinated by the history of words and phrases that have more than just a literal meaning. Why does it “rain cats and dogs”? How did “eavesdropping” come to mean listening furtively to other peoples’ conversations? And is a touchstone an actual stone?

A touchstone, as used in casual conversation, can mean two things:

  • A way to measure the quality of something, as in “His athletic success became a touchstone for future athletes at the school”
  • An essential part of something, as in “Nirvana was a touchstone of the grunge music scene in the 1990s”

Where does the word touchstone come from?

According to that most wonderful of resources Wikipedia, a touchstone is an actual stone. More precisely, it’s a small stone tablet used to determine the quality of precious metals like gold and silver. When you use gold to draw a line on a touchstone, it leaves a streak, the color of which can be compared to streaks from gold pieces of known quality and composition.

Fascinating, right? Although explaining why it’s popular today is much harder, like trying to explain why we use “what’s up?” to greet people. Who knows, maybe some famous person decided to use it and it spread from there.

Now I’ll answer the first 2 questions with less precision.

In England several centuries ago, when it rained really hard, stray dogs and cats would drown and pile up in the gutters. Thus the phrase “it’s raining cats and dogs”. Makes you think twice about using that phrase, right?

As for eavesdropping, there are several competing explanations, but old houses used to have eaves hanging from their roofs. Thus if you were right outside the window or door, secretly listening to the conversations inside, you’d be beneath the eaves and thus eavesdropping.

What words or phrases can you explain? I’d love to hear.