Erik the cat sitting in an overnight bag
7 April 2021
To let the cat out of the bag is to reveal a secret. But where does this idiom come from? What is the cat doing in the bag and what has this to do with secrets?
The answer is a disappointing, “we don’t know.” The metaphor underlying the phrase has been lost to the ages. There is a similar phrase in French, vider le sac, literally meaning to empty the sack and used to mean to tell the whole story or finish the tale. The English version could be a more colorful variation on that. But there is also a long history using opening something as a metaphor for revelation (and the Latin roots of the word reveal literally mean an uncovering), from the ancient Greek myth of Pandora’s box to the recent open one’s kimono. So, countless speculative candidates are possible (and unevidenced).
The phrase first appears in print in 1760 and likely dates in oral use to the decades immediately preceding—we have a raft of print appearances in the 1760s, indicating that it was a faddish term during that decade. The first appearance is in April 1760 in a brief book review of Willoughby Mynors’s The Life and Adventures of a Cat in the Edinburgh Magazine (a verbatim review appears in the London Magazine of the same date):
The life and adventures of a cat, 2 s. 6d. Mynors.
We could have wished that the strange genius, author of this piece, had not let the cat out of the bag; for it is such a mad, ranting, swearing, caterwauling puss, that we fear no sober family will be troubled with her.
It’s clear from the context that the phrase was already in circulation by this date and that the reviewer is making a play on words, juxtaposing the idiom with the title of the book in question.
Let the cat out of the bag is also recorded in eighteenth-century stockbroker slang. From Thomas Mortimer’s 1761 Every Man His Own Broker: or a Guide to Exchange-Alley:
TERM generally begins a few days before the drawing of the lottery, when those who have contracted to take, or are already possessed of, more tickets than they can possibly hold, (in the language of ’Change Alley, begin to open the budget or to let the cat out of the bag) and these may not improperly be stiled BULLS, PLAINTIFFS;—and the opposite party, who have agreed to deliver a quantity of tickets without being possessed of them, the BEARS, DEFENDANTS.
To open the budget is an obsolete idiom meaning to speak one’s mind. In the idiom budget is used in the now obsolete sense of a purse or wallet, so that idiom is yet another revelatory metaphor.
Let the cat out of the bag also appears in a 1762 English translation of Molière’s play The Gentleman Cit (Le Bourgeois Gentilhomme):
Mad. JORDAN.
And pray what does this same nobleman do for you?Mons. JORDAN.
Why, things that would surprize you, if you knew them all.Mad. JORDAN.
And what are they?Mons. JORDAN.
No, hold there, wife; I shall not let the cat out of the bag neither. It is sufficient that if I have lent him money, he will pay it me all again very soon.
Yet another early appearance is again from the world of the stock market, in the East India Examiner of 5 November 1766 in a passage talking about what we now call insider trading:
Any fixed value given to India stock, however great, cannot suit their views; their business is to keep it at a low uncertain value, as we find it at present, while they behind the curtain, knowing the time when they shall raise the dividend 2 per cent, and consequently the stock 50 per cent. more in value, in the mean time always declaring an increase of dividend premature, will be able by themselves and their friends with money prepared, to purchase gradually, and imperceptibly, the bulk of the Company's stock, and then let the cat out of the bag.
As mentioned above, there are countless possibilities as to the original metaphor underlying the phrase. I will only discuss the two most common, two that are almost certainly false.
The first one, and one that can be found repeated many etymological resources (including old versions of this site) is that it refers to a scam in which a cat would be surreptitiously substituted for a suckling pig that had just been purchased at market. The cat would be placed in the bag in the hopes that the customer would not look into it until they were some distance away. This same alleged scam is often also held to be the origin of the phrase to buy a pig in a poke. But there is no evidence of such a scam existing, or at least being common, and early uses of the phrase are not in contexts that are related to any such scam. This explanation would appear to be a post hoc rationalization for an idiom of unknown origin.
The second common, but almost certainly false, explanation is that let the cat out of the bag refers to the cat o’ nine-tails used on board ships as form of punishment. The whip would be kept in a special bag to protect it from the sea air and to let the cat out of the bag was to confess a crime worthy of flogging. Again, a neat tale, except again there is absolutely no evidence to connect the phrase with a nautical origin. None of the early citations are even remotely connected to life on the sea.
To sum up, we don’t know where let the cat out of the bag comes from or what it originally referred to. All we know is that the phrase probably arose in the early to mid eighteenth century and appears in print by 1760.
Sources:
The East India Examiner (No. 10. 5 November 1766). London: W. Nicoll, 1766, 88–89. HathiTrust Digital Archive.
Mikkelson, Barbara. “What’s the Origin of ‘Letting the Cat Out of the Bag’?” Snopes.com, 8 August 2010.
Molière. “The Gentleman Cit.” The Comic Theater, vol. 5 of 5. Samuel Foote, trans. London: Dryden Leach for J. Coote, 1762, 202. HathiTrust Digital Archive.
Mortimer, Thomas. Every Man His Own Broker: or a Guide to Exchange-Alley. London: S. Hooper, 1761, 70–71. Eighteenth Century Collections Online (ECCO).
“New Books, With Remarks and Extracts.” The Edinburgh Magazine, April 1760, 224. Gale Primary Sources: American Historical Periodicals from the American Antiquarian Society,
Oxford English Dictionary, second edition, 1989, s. v. bag, n.
Photo credit: David Wilton, 2020.