We might expect ‘as thick as thieves’ to be a variant of the other commonly used ‘thick’ simile ‘as thick as two short planks’. The fact that the former expression originated as ‘as thick as two thieves’ gives more weight to that expectation.
As you may have guessed from that lead in, the two phrases are entirely unconnected. The short planks are thick in the ‘stupid’ sense of the word, whereas thieves aren’t especially stupid but are conspiratorial and that’s the meaning of ‘ thick’ in ‘as thick as thieves’.
‘Thick’ was first used to mean ‘closely allied with’ in the 18th century, as in this example from Richard Twining’s memoir Selected Papers of the Twining Family, 1781:
Mr. Pacchicrotti was at Spa. He and I were quite ‘thick.’ We rode together frequently. He drank tea with me.
Like all ‘as X as Y’ similes, ‘as thick as thieves’ depends on Y (thieves) being thought of as archetypally X (thick). The thieves had some competition. Earlier versions were ‘as thick as’… ‘inkle weavers’, ‘peas in a shell’ and ‘three in a bed’, all of which were examples of things that were especially intimate (inkle-weavers sat at looms that were close together).
These variants have now pretty much disappeared, leaving the way clear for ‘as thick as thieves’.
The association of thieves with conspiratorial and secretive language was well established in England in the 18th century. Many of those on the fringes of society, for example poachers, homosexuals, street hawkers and thieves, used secret words and phrases to converse furtively amongst themselves.
Backslang was one example of this, the best known survival of backslang being ‘yob’ for ‘boy’. Several lexicographers had published dictionaries used by those on the wrong side of the law, notably the New Dictionary of the Terms Ancient and Modern of the Canting Crew, 1698.
The ‘canting crew’ were the various vagabonds and coney-catchers (conmen) that inhabited the streets of British cities. The dictionary explained how to decipher the language of “the tribes of gypsies, beggars, thieves, cheats etc.”, so that people could “secure their money and preserve their lives”.
Given that thieves were established as being ‘thick’ by the late 17th century it is surprising that ‘as thick as thieves’ didn’t emerge until a century or so later. The records of the Old Bailey, which list transcripts of cases held there since 1674 and which might be just the place to find this phrase, don’t list it until 1874.
The first example that I can find of it in print is from the English newspaper The Morning Chronicle, in a letter dated March 1827, published in February 1828:
Bill Morris and me are as thick as two thieves.
So there you have it; proverbially at least, planks are stupid but thieves (unless you include bankers) aren’t.
A selection of wonderful little illustrations found in a Fifteenth Century Book of Hours attributed to an artist of the Ghent-Bruges school and dating from the late 15th century.
In the pages without full borders the margins have been decorated with an array of different images depicting flowers, birds, jewellery, animals, household utensils and these superb rainbow-coloured ‘grotesques’.
In 1934 Ernest Hemingway wrote down a list of two short stories and 14 books and handed it to a young out-of-work writer Arnold Samuelson (many of the texts you can find in the Open Culture collection of Free eBooks):
A postcard from the 1800s shows the seven dwarfs finding Snow White asleep in their bedroom. Hulton Archive/Getty Images
The Original Folk & Fairy Tales of the Brothers Grimm
by Jacob Grimm, Wilhelm Grimm, Jack Zipes and Andrea Dezso
It’s well-known that our favorite fairy tales started out darker than the ones Disney animators brought to life. But you might be surprised by how much darker the originals were.
For the first time, a new translation of the Brothers Grimm’s tales reveals exactly how unsanitized and murderous the bedtime stories really were.
Jack Zipes, author of The Original Folk and Fairy Tales of the Brothers Grimm, is the only person who has ever translated the first edition of their tales into English.
“Some of them are extremely dark and harrowing,” Zipes tells NPR’s Rachel Martin. “Many are somewhat erotic and deal with incest. Most of them are not what we call fairy tales; they tend to be animal tales or warning tales.”
Take, for example, Snow White. In the modern version of the tale, the Evil Queen is Snow White’s stepmother.
But in the first edition, Snow White is only 7 years old, and it’s her biological mother who wants to murder her for her beauty.
The stories are hardly appropriate for children by today’s standards, and at the outset, they weren’t intended to be.
The Grimms “collected these tales to show what life was like,” says Zipes. “And they wanted to reveal what they considered the divine truths of the tales.”
And the tales endure. Zipes says that’s because they resonate in every era. “I think they speak to the human condition. …
They also provide hope. For the most part, there is social justice in these tales and … we need that. We need the hope that these tales provide.”