Gadzooks! The Surprising Sources Of Great Sayings

- Jacopo Della Quercia

“To steal one’s thunder”

Thor and young-adult demigod Percy Jackson may be fiction’s most celebrated thunder stealers, but it was an 18th-century dramatist named John Dennis who popularized the phrase. Dennis invented a device to simulate the sound of thunder for his plays—so clever that a rival dramatist copied his method for a production of Macbeth. “Eternal curses light on these scoundrels!” Dennis is said to have declared. “They have stolen my thunder and don’t know how to roll it!”

“Let the cat out of the bag”

Who would even put a cat in a bag? The answer may lie in medieval markets, where people used to sell piglets tied in bags for farmers to carry home. A shady dealer might swap the piglet in the sack with a less expensive animal, such as a cat. So when you let the cat out of the bag, you were exposing the con to everyone.