A Bizarre Phrase with a Surprisingly Real Origin
Some idioms sound so strange, it’s hard to imagine they ever made sense. Take “let the cat out of the bag.” Unless you’re a wizard, a butcher, or running a medieval pet shop, you probably haven’t kept a cat in a sack lately.
So how did this peculiar phrase come to mean revealing a secret?
Let’s unpack the sack — literally and linguistically.
🐷 Medieval Markets and Marketplace Mischief
The most widely accepted origin of “let the cat out of the bag” goes back to the medieval European marketplaces. Farmers and vendors would sell piglets — a valuable commodity — tied up in a “poke bag” (a small sack). Honest sellers would let buyers inspect the pig before purchase.
But some shady dealers? Not so much.
They would secretly swap the piglet for a worthless cat — easier to catch, cheaper to supply, and, unfortunately for buyers, similar in size when bundled up.
If the buyer opened the bag to check their purchase before paying, they’d “let the cat out of the bag” — and expose the scam.
Thus, the phrase evolved to mean revealing something that was supposed to remain hidden.
🧺 Bonus Phrase Connection: “Pig in a Poke”
Ever heard the expression “don’t buy a pig in a poke”? That’s a sister idiom with the same origin.
Buying a “pig in a poke” means making a purchase (or decision) without verifying what you’re getting. If you don’t open the bag, you might walk away with a cat instead of a pig.
So:
- “Buy a pig in a poke” = don’t check what’s inside = bad idea.
- “Let the cat out of the bag” = you checked = scam revealed.
Two idioms, one market scam.
🧠 When Did It Become a Metaphor?
By the 1700s, the literal market con began turning into metaphor. People started using the phrase when secrets were accidentally revealed — not about livestock, but about plans, surprises, or gossip.
Examples:
- “She let the cat out of the bag about the surprise party.”
- “His expression let the cat out of the bag before he even spoke.”
The meaning had shifted, but the imagery — of something slipping out unexpectedly — was too good to let go.
😹 Why a Cat?
Of all the animals, why a cat?
Cats are:
- Hard to control
- Noisy when startled
- Quick to flee when released
It’s the perfect metaphor for a secret that escapes your control. Once it’s out, you can’t shove it back in.
💬 Modern Use of the Phrase
Today, “let the cat out of the bag” is an everyday idiom you’ll hear in casual conversation, news headlines, and even business:
- “Oops, I let the cat out of the bag — the product launches next week.”
- “He let the cat out of the bag before the press release.”
It means someone disclosed information too early, usually by accident.
It’s close in meaning to:
- “Spill the beans”
- “Blow the surprise”
- “Reveal the secret”
✍️ A Quick Sentence Guide
| Situation | Example |
|---|---|
| Casual | “Don’t let the cat out of the bag — she doesn’t know yet.” |
| Formal | “The executive let the cat out of the bag during the interview.” |
| Funny | “Grandpa let the cat out of the bag five minutes into keeping a secret.” |
🧠 Final Thought: Language as a Time Machine
What makes idioms like this so fascinating is that they carry echoes of how people actually lived. With just a few words, you’re transported back to muddy markets, handmade sacks, and shouting farmers trying to protect (or fool) their customers.
Every time you say “let the cat out of the bag,” you’re reenacting centuries-old advice:
Check before you commit — and be careful what slips out.
