Ever let slip something you shouldn’t have and been accused of letting the cat out of the bag? Unless you’re involved in some odd feline activities, you’re probably not letting an actual cat out of a bag, so where does the idiom come from?

As with quite a lot of apocryphal etymology, one theory suggests that this phrase has naval origins, and that the cat in question is a form of whip rather than a feline. The cat o’ nine tails was a type of whip commonly used on boats to punish sailors who committed transgressions. It was in widespread use well before the first recorded use of the phrase, ‘let the cat out of the bag’ in ‘The London Magazine’ in 1760, making it feasible that they could be related. The cat o’ nine tails was a particularly nasty form of punishment, as the whip consisted of nine cords. Traditionally, rope was made by plaiting three strands of yarn together to make a thin rope, and then three strands of the thin rope were plaited together to make the finished product. A cat o’ nine tails was made by unplaiting this rope to give nine separate strands, which was then used to whip the sailors. It was probably called ‘cat o’ nine tails’ because of the claw-like scratches it inflicted, and was commonly referred to simply as ‘the cat’. One theory is that ‘let the cat out of the bag’ comes from the sight of the cat o’ nine tails being produced as a form of punishment, but it’s not clear why this would be linked to the idea of a revelation of a secret.

“As with quite a lot of apocryphal etymology, one theory suggests that this phrase has naval origins.”

Much more likely as the origin of the phrase are some dodgy mercantile dealings at markets as early as the 16th century. In a practice we would consider horrendously inhumane these days, traders would often sell piglets in bags, referred to as ‘a pig in a poke’. Though this seems a strange expression today, a ‘poke’ is simply a bag or a sack, originating from the French word ‘poque’ of the same meaning. The term is still in use in some countries like Scotland and the USA. Pigs in pokes have given rise to an idiom of their own: ‘don’t buy a pig in a poke’. It’s essentially the vernacular version of ‘caveat emptor’, or ‘buyer beware’ in Latin; if you’re buying a pig in a poke, you should always open the bag to see what you’re buying and make sure it’s what you expect. Market traders had a bit of a habit of swapping the piglets, which were fairly valuable, for something much less valuable: feral cats.

And so we return to our expression ‘let the cat out of the bag’. The accepted theory is that this phrase arises from the experience of opening the poke and releasing a (presumably rather angry) cat, instead of a piglet. It accounts for comments like writer Will Rogers’ that, ‘Letting the cat out of the bag is a whole lot easier than putting it back in’. If the cat in question were the cat o’ nine tails, putting it back in wouldn’t be that difficult at all, unlike with a feral cat. It might be a little hard to image how you could mistake a hissing cat in a bag for a much more docile piglet, but it certainly would explain the sense of revealing an unpleasant or undesirable secret, especially since feral cats were obviously worth much less than piglets. If nothing else, there were a lot more of them knocking around on the streets – perhaps because of the apparently common phenomenon of the sky raining cats and dogs.

Of course, the phrase ‘raining cats and dogs’ isn’t literally true; cats and dogs did not actually fall from the sky. But, sadly, it’s entirely possible that this phrase does originate from a link between heavy rain and the sudden appearance of lots of animals. Back in the 17th and 18th century, drainage in the streets wasn’t exactly perfect, and the streets would often flood, allowing the torrent of rain to carry along with it any debris from the roads. It wasn’t uncommon for this debris, as well as butchers’ scraps and sewage, to include the corpses of cats and dogs, most of which were strays that had either starved previously or were drowned by the rain. It’s an occurrence described by Swift in his poem ‘A Description of a City Shower’, as he writes:

“Sweeping from Butchers Stalls, Dung, Guts, and Blood,

Drown’d Puppies, stinking Sprats, all drench’d in Mud,

Dead Cats and Turnip-Tops come tumbling down the Flood.”

It seems to be presented as something his readers would quickly recognise, making it common enough that an idiomatic connection could be formed between heavy rain and a sudden flow of cats and dogs.

WordUp: Larry, Bob, and Parker

Unfortunately, a lot of our animal idioms seem to arise from various forms of animal cruelty. I suppose we can only be glad that the practice of selling live pigs in bags is no longer commonplace, and that it’s only secrets, not real cats, that we’re likely to uncover.