Picture this: it’s 1616, London is buzzing with theatre, Shakespeare is still alive, and a playwright named Ben Jonson is about to accidentally give the English language one of its most beloved idioms. The phrase “when pigs fly” — something you’ve probably said dozens of times — has roots that stretch back over four centuries, tangled up in a satirical comedy called The Devil is an Ass. And the story of how these two expressions got linked is stranger, funnier, and more layered than you’d expect.
What Is “The Devil is an Ass” — and Why Does It Matter?
The Devil is an Ass is a Jacobean comedy by Ben Jonson, first performed in 1616 and first published in 1631. It was based, partially, on the events of the famous Leicester Boy Witch Trial. The premise is brilliantly comic. The play opens in Hell, where Satan and an inferior devil named Pug are in conversation. Pug desperately wants to be sent to Earth to do the Devil’s work — but Satan thinks he isn’t up to the job. The world has grown so sophisticated in its vices, especially in the moral cesspool of London, that a simple devil like Pug will be severely out of his depth.
And sure enough, that’s exactly what happens.
Pug finds himself outwitted by the cunning and greed of London’s inhabitants. The central human character, Fabian Fitzdottrel, is a foolish gentleman obsessed with wealth and the occult. He attempts to summon a devil to gain riches, only to be deceived by con artists instead.
The core joke — the one Jonson hammers home with genuine satirical genius — is that humans are often more devious than the devil himself, making the devil appear as an “ass” or fool. It’s a dark, brilliant insight wrapped in farce. And in 2026, it still lands.
So Where Do Pigs Come Into This?
Here’s where the history gets a little muddy — and a lot more interesting.
The exact phrase “when pigs fly” does not appear in The Devil is an Ass. Many people online claim it does, and the claim has spread widely enough to feel like established fact. But it isn’t quite that simple.
What we do know is that both expressions share the same cultural moment. The idiom’s earliest known print reference appears in John Withals’ 1616 dictionary, which mentions “pigs fly in the ayre with their tayles forward.” That’s the same year Jonson’s play was first performed. The two weren’t necessarily connected — but they were born in the same era, breathing the same air of scepticism, satire, and dark humour.
The phrase “when pigs fly” is an adynaton — a figure of speech so hyperbolic that it describes an impossibility. The implication is that the circumstances in question will never occur. The phrase has been used in various forms since the 1600s as a sarcastic remark.
Think of an adynaton as language’s way of rolling its eyes. It’s sarcasm baked into grammar. And Jonson’s play? It’s essentially a two-hour theatrical adynaton — the premise itself is impossible, absurd, and designed to expose human folly.
How Two Expressions Got Fused Together
The phrase “The devil is an ass when pigs fly” isn’t a direct Jonson quote. It’s what linguists and internet culture historians might call a compound idiom fusion — two separate expressions stitched together over time because their meanings rhyme thematically.
Think of it like this: if “the devil is an ass” means the world is more corrupt than evil itself can manage, and “when pigs fly” means something that will never, ever happen — then putting them together creates a kind of double-barrel impossibility. The devil being an ass? That’s absurd. When pigs fly? Also absurd. Together, they amplify each other.
The central theme of The Devil is an Ass is the satire of human folly, especially focusing on greed, corruption, and the foolishness of those who are easily deceived by appearances and flattery. Strip that down, and it maps perfectly onto the spirit of “when pigs fly” — a phrase used to scoff at over-ambition and wishful thinking.
That thematic echo is likely what drew the two together in popular use.
Ben Jonson: The Man Who Watched Human Greed Up Close
You can’t really understand The Devil is an Ass without understanding who wrote it. Ben Jonson was a man of vast reading and a seemingly insatiable appetite for controversy. He had an unparalleled breadth of influence on Jacobean and Caroline playwrights and poets. But he wasn’t some detached academic. He was a bricklayer, a soldier, and a repeat-offender felon — someone who’d actually lived inside London’s social chaos.
Jonson’s comedies, conceived in the crabbed spirit of Roman satire, are filled with now-obscure allusions to urban society that came naturally to a lifelong Londoner. His plays weren’t fantasy escapes. They were mirrors held up to real people doing real, greedy, embarrassing things.
As scholar Peter Happé noted in his critical edition of the play, The Devil is an Ass offers a window into Jacobean theatrical style and cultural concerns that no Shakespeare play quite replicates — it’s grittier, angrier, and more cynically funny. Industry experts in early modern drama consistently highlight it as Jonson’s most underrated work.
What makes it remarkable is that according to recent studies in Renaissance theatre scholarship, The Devil is an Ass is partially a summary of Jonsonian dramatic innovation to date, linking with many past plays including Volpone, Epicoene, The Alchemist, and Bartholomew Fair. In other words, it was Jonson’s artistic self-portrait — a “this is who I am” statement in play form.
Why This Story Still Resonates in 2026
Here’s the thing about folly and greed: they don’t go out of fashion.
The basic plot of The Devil is an Ass — a naive outsider arrives somewhere, expecting to cause chaos, and gets completely outmanoeuvred by the locals — could describe half the startup culture of the last decade. Or any number of political scandals. The con artists in Jonson’s London aren’t that different from the grifters of our own news cycle.
Contemporary audiences can still recognise the themes of corruption, greed, and vanity in today’s political and social arenas. That’s not a critical stretch — it’s just an honest read of the play.
And “when pigs fly”? It’s still everywhere. People use it in casual conversation, in headlines, in social media comments dismissing unlikely promises. The adynaton hasn’t lost its punch after 400 years. If anything, it’s sharper. We live in an age of announcements that never materialise, of promises made with no intention of keeping them. Saying “when pigs fly” still carries exactly the weight Jonson would recognise.
Here’s a quick breakdown of what makes both expressions endure:
- They’re emotionally satisfying — saying “when pigs fly” feels good as a dismissal
- They’re visually absurd — a flying pig is genuinely funny to imagine
- They’re culturally transferable — versions of this idiom exist across Spanish, French, and other European languages
- They’re truthful — the underlying cynicism is, honestly, often warranted
The “When Pigs Fly” Moment in Alice in Wonderland
One more piece of the puzzle worth knowing. The phrase appears in the 1865 Alice’s Adventures in Wonderland. Lewis Carroll used it in that deliberately surreal, logic-defying world — which is fitting, because Alice is essentially a story about impossibilities becoming real. It’s the perfect home for a pig that flies.
Carroll’s use helped cement the phrase in mainstream English culture, two and a half centuries after Jonson’s era. By then it had already crossed from street-level Scottish proverb to literary classic. That’s a long journey for a barnyard animal.
Conclusion
The next time someone says “when pigs fly” and dismisses something as impossible, you’re hearing a 400-year echo of London’s theatre district — of Ben Jonson’s sharp, furious, funny observation that humans have always been greedier and more foolish than any devil could ever be. The devil is an ass when pigs fly isn’t just a phrase. It’s a compressed philosophical argument: the world is absurd, people are ridiculous, and the impossible happens about as often as pigs sprout wings. Jonson knew it. We still know it. And somehow, that’s both depressing and deeply comforting.
FAQs
Q1: Did Ben Jonson actually write the phrase “when pigs fly” in The Devil is an Ass?
No — not exactly. The phrase doesn’t appear verbatim in the play. The closest confirmed early print use is in John Withals’ 1616 dictionary, published the same year the play premiered. The two share a cultural moment but aren’t directly linked.
Q2: What does “the devil is an ass” actually mean?
It means the devil is a fool — because in Jonson’s play, human beings are so corrupt and devious that even Satan’s own servant can’t compete with them. The phrase satirises human greed by suggesting we’re worse than evil itself.
Q3: What is an adynaton, and how does “when pigs fly” qualify?
An adynaton is a figure of speech that expresses impossibility through absurd exaggeration. “When pigs fly” qualifies because pigs flying is physically impossible, making it a perfect stand-in for anything that will never, ever happen.
Q4: Is The Devil is an Ass still performed today?
Yes. Modern theatre companies have staged it, though it requires creative interpretation to make Jonson’s dense 17th-century satire accessible to contemporary audiences. It’s considered one of his most underrated works.
Q5: Where does the “pigs might fly” variant come from?
A Scottish proverb recorded around 1639 used “pigs may fly” — suggesting the expression had been circulating orally before that. The Scottish origin theory is widely cited in etymological research, alongside the Withals 1616 dictionary reference.
