You have certainly heard this common phrase used when someone has exposed a secret, usually accidentally. But have you ever stopped to think about where it came from and, in the first place, what was a cat doing in a bag?
For those who are not familiar with the expression, the idiom “let the cat out of the bag” means exposing a secret or revealing previously concealed information. It can also be used to refer to someone who is a “blabbermouth.” A cat, playing the part of the “secret,” sprinting out of the “bag,” playing the role of where the secret was hiding, offers quite the picture. Just like a cat that was once stuck in a cage, it’s never going to go back into that bag again once that secret is out.
Where did that phrase start from? Well, first, let’s remember the phrase’s first documented use. The reviewer complained in a 1760 book review in the London Magazine that he “wished that the author had not let the cat out of the bag,” probably referring to some form of plot point.
But although the phrase’s first recorded use is quite clear, its root is not. Unfortunately, with many idioms like these, it is difficult to pin down a specific root, simply because of the way language develops. People gradually, over time, start using words, and there is no concrete historical record of how they came up with that phrase. This is particularly the case for figurative phrases, which do not actually imply what they say, by definition.
So there is no definite consensus as to where it comes from, but there is an explanation that, at least very likely, most linguists accept. And it actually includes, literally, cats in bags!
Dating back to the Middle Ages, the most common reason for why we say “let the cat out of the bag.” As the tale goes, in medieval markets, shady livestock sellers tried to swindle their customers. The seller would instead sneak a cat into the bag if anyone wanted to purchase a pig, cheating the buyer out of the higher price for a pig. It wasn’t until the customer came home and, basically, let the cat out of the bag that they would know they were scammed, thus the association of the word with sharing a secret. There is no lack of idioms in English for sharing a secret, so we often call it “spilling the beans.” This explanation is not fully confirmed, and neither, in fact, is the tale that medieval vendors have even made such a switcheroo on a regular basis.
There’s another hypothesis about this expression’s roots, and it’s a lot darker. This theory argues that the “cat” to which the word refers is not a feline but the “cat o ‘nine tails,” a whip made of nine intertwined cords that was used in the British Royal Navy and in jails until as late as the 1840s as a means of punishment. It was called a “cat” because the markings it left resembled scratches on its victims. In short, please don’t put the cat in the bag in the first place. Meow.
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