I have searched and failed to find the origin of the term "Someone let the cat out of the bag".

Wikipedia defines letting the cat out of the bag

Letting the cat out of the bag is a colloquialism meaning to reveal facts previously hidden. The facts were usually hidden from a specific target audience or theatrical audience. Examples include:

  • revealing a conspiracy (friendly or not) to its target
  • in a movie or play, the revelation of a plot twist
  • letting an outsider into an inner circle of knowledge (e.g., explaining an in-joke)

But admits “The derivation of the phrase is not clear.” And likewise do The Phrase Finder and Mental Floss who all cite the same two origins; namely, cat o' nine tails, and pig in a poke. It seems nobody has a definite answer.


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    That's because its origin, like the origin of almost everything in English, is lost in the mists of time. Anybody who's familiar with cats can understand that metaphor, and that includes people speaking pre-English languages. In other words, there is no evidence for a specific origin. Commented May 10, 2017 at 13:32
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    There are two commonly heard suggested origins of this phrase. 1) One relates to the fraud of substituting a cat for a piglet at markets. If you let the cat out of the bag you disclosed the trick - and avoided buying a pig in a poke (bag). This form of trickery is long alluded to in the language and 'pigs in a poke' are recorded as early as 1530. --- 2) The other theory is that the 'cat' referred to is the cat o' nine tails, which was used to flog ill-disciplined sailors. phrases.org.uk/meanings/let-the-cat-out-of-the-bag.html
    – user66974
    Commented May 10, 2017 at 13:33
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    The first documented use of the phrase in the sense of “revealing a secret" comes from a book review in a 1760 issue of The London Magazine, wherein the reviewer laments that, "We could have wished that the author had not let the cat out of the bag." - That, unfortunately, is about all we know for sure. There are two popularly cited origins for the phrase, but neither is very clearly recorded as leading to it. - mentalfloss.com/article/31180/whats-origin-let-cat-out-bag
    – user66974
    Commented May 10, 2017 at 13:38
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    @JohnLawler - the "mists of time" are not a good excuse to stop searching. It is like asking an archaeologist to stop digging.
    – user66974
    Commented May 10, 2017 at 18:05
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    I added the "research" because the question has four votes in favour of closure. If you show the "research" users are then left with nothing to object....most of the time. Anyhow, good luck!
    – Mari-Lou A
    Commented May 11, 2017 at 5:50

1 Answer 1


I do not say "evidently" unadvisedly when I say that evidently the origin of 'let the cat out of the bag' considerably postdates 'the mists of time'. The date of the earliest recovered fossil of the latter phrase in OED is 1701:

And who see clearly thro' the Mists of Time, Those puzling Glooms where busy Mortals stray.

Ladies Defence, Mary Chudleigh, 1701. Emphasis mine; quote from OED collection.

However, a latter-day parting of those mists reveals an earlier fossil, dating from 1682:

And thus those Druides that formerly had dominion of the Britons Faith, become now to be helpers of their joy, and are become the leaders of the blind people in a better way, and unto a better hope; and held forth that Light which through Gods mercy hath continued in this Island ever since, through many Storms and dark Mists of time, until the present Noon-day.

An historical and political discourse of the laws & government of England, Nathaniel Bacon and John Selden, published 1682. Bolding mine.

Note that both authors of An historical and political discourse were dead by 1660, and thus that the "mists of time" must needs have preceded that date.

As mentioned, contemporary evidence dates 'let the cat out of the bag' to 1753, nearly a century after the mists of time parted for Bacon and Selden's "present Noon-day":

We hear from Rochester, a few Days past, there was held, at the Sign of the Drone in that City, a great Meeting of Pursers, Place Hunters, with Artificers of such Sort, to consider of inviting one or two Gentlemen to offer as Candidates to represent that City at the next General Election. It is thought in vain for any Gentleman to offer himself there until the Ad —— please to turn the Cat out of the Bag for them, which is not yet untied.

Caledonian Mercury, 27 December 1753 (paywalled).

The 1753 date is an earlier fossil than that unearthed from 1760 by Farmer and Henley, as referenced in 1890 in Slang and its analogues past and present:

  1. The Life and Adventures of a Cat, pr. 2s. 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.]

The London magazine, or, Gentleman's monthly intelligencer, v 29, p 224, 1760.

Farmer and Henley remark the origin known to them, thus contributing what is the earliest evidence available concerning the origin of the 'let the cat out of the bag' phrase:

TO LET THE CAT OUT OF THE BAG, phr. (common). To reveal a secret; a variant with a slightly modified sense is TO PUT ONE'S FOOT IN IT. [This and the kindred phrase 'to buy a pig in a poke,' are said to have had their origin in the bumpkin's trick of substituting a cat for a young pig and bringing it to market in a bag. If the customer were wary THE CAT WAS LET OUT OF THE BAG, and there was no deal.]

Slang and its analogues past and present, John S. Farmer and W. E. Henley, 1890.

For my part, I uncovered no other origin story than that given by Farmer and Henley in 1890. Without evidence, the story that the origin of the phrase came from the practice of storing a cat-o-nine-tails in a bag is apocryphal and, because of its failure to evoke any other than unevidenced and fabulous sense consonant with the early meaning of 'let the cat out of the bag', barely credible.

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    +1 - thanks for digging out more language fossils.
    – user66974
    Commented May 11, 2017 at 5:37

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