The phrase when pigs fly is one of the English language’s most vivid ways to declare that something will never happen, yet few modern speakers realize that its journey from rural proverb to theatrical punchline passes directly through Jacobean London. In practice, in Ben Jonson’s 1616 satirical comedy The Devil Is an Ass, the idea of airborne swine becomes far more than a throwaway joke. It serves as a barometer of human gullibility, a benchmark for the impossible, and a fitting emblem for a play that argues humans have become so thoroughly corrupt that even the devil himself looks naive by comparison.
The Devil Is an Ass: A Satirical Masterpiece
To fully appreciate the adage’s place in the work, it helps to understand what makes The Devil Is an Ass one of Ben Jonson’s most biting—and surprisingly modern—comedies. Written during a peak period of Jonson’s career, the play arrived just a year after his controversial Bartholomew Fair and reflects the dramatist’s lifelong obsession with human hypocrisy, social climbing, and the gap between appearance and reality.
The plot centers on a minor devil named Pug, who pleads with Satan for a chance to tempt mortals on Earth. Convinced that he can corrupt souls in the teeming, sinful environment of London, Pug is nevertheless warned by his master that human beings have grown so sophisticated in their villainy that a lesser demon stands no chance. Satan reluctantly agrees, and Pug arrives in the city only to be outwitted, exploited, and utterly baffled by the very mortals he intended to damn. The central joke of the play is that the Devil is, quite literally, an ass—foolish, outdated, and outmatched—while the supposedly fallen humans around him manage fraud, greed, and social pretension with breathtaking skill.
Jonson peoples the stage with a gallery of recognizable urban types: the gullible gentleman Fitzdottrel, who is obsessed with the occult; the manipulative con artists who prey on him; and a host of lawyers, courtesans, and witches who treat deception as a vocational art. In this mercantile world of advanced scheming, the supernatural feels almost quaint And that's really what it comes down to..
Not obvious, but once you see it — you'll see it everywhere And that's really what it comes down to..
The Proverb of Flying Pigs in Early Modern English
Jonson did not invent the image of a pig with wings, but he was among the earliest major English playwrights to give the adage prominent theatrical life. Variants of the expression—pigs may fly, when swine fly, and, by the seventeenth century, the closer modern form when pigs fly—had already circulated in oral tradition across England and Scotland as a humorous benchmark for impossibility. By embedding this folk wisdom into The Devil Is an Ass, Jonson transformed a barnyard joke into a sophisticated satirical tool.
Short version: it depends. Long version — keep reading.
In the context of the play, the notion that pigs might fly is invoked precisely because so many characters are willing to believe in absurdities. Even so, fitzdottrel, for instance, is prepared to accept that a minor demon has come to serve him, that witchcraft can solve his debts, and that theatrical costumes confer magical power. If a Londoner of Jonson’s era would dismiss flying pigs as impossible, why, the playwright asks, do the same people fall for financial scams, social pretenders, and supernatural promises that are equally ridiculous? Against this backdrop of deluded credulity, the proverb functions as a kind of tragicomic litmus test. The swine never leave the ground, yet the human capacity for self-deception seems to soar Most people skip this — try not to. Turns out it matters..
Why the Impossible Matters to Jonson’s Satire
The genius of The Devil Is an Ass lies in its structural irony. Pug expects to find a world of innocents waiting to be tempted; instead, he finds a metropolis where temptation has already been industrialized. And humans lie, cheat, and betray with such efficiency that they render the devil redundant. In one of the play’s most telling reversals, Pug’s earthly body ends up in jail for crimes he did not commit, while the truly guilty parties walk free, enriched by their malice.
Against this reality, the phrase when pigs fly takes on a deeply cynical shading. Jonson suggests that the only truly impossible thing in his London would be an honest man, a fair trial, or a social climber satisfied with his station. The animals may remain wingless, but human iniquity knows no bounds. By yoking a harmless rural proverb to the urban corruption onstage, Jonson creates a dissonance that still feels sharp today: we readily laugh at the image of a flying pig, yet we often fail to recognize equally absurd falsehoods when they arrive dressed in the jargon of commerce, law, or fashionable superstition.
Some disagree here. Fair enough.
The play also participates in a wider Early Modern fascination with proverbial speech. That's why jonson, ever the classical satirist, uses the flying-pig motif not merely for laughs but as moral punctuation. Here's the thing — audiences of the period cherished dramatic dialogue that sparkled with familiar adages, and playwrights frequently competed to repackage folk wisdom in ways that felt fresh. Each time a character ignores the impossible in pursuit of personal gain, the audience is reminded that such folly is older than the London marketplace and universal enough to have its own proverb.
From the Jacobean Stage to Modern Idiom
While The Devil Is an Ass disappeared from the active repertory for long stretches after the seventeenth century, the language it helped preserve lived on. Consider this: When pigs fly survived in rural dialects before re-emerging in nineteenth- and twentieth-century English as a stock retort to unlikely promises. Today, the expression appears in boardrooms and schoolyards alike, a testament to the durability of agrarian imagery in an urbanized world.
For literary historians, Jonson’s play remains a crucial waypoint in the idiom’s written record. That's why contemporary revivals and academic studies of the play often highlight this connection precisely because it demonstrates how deeply embedded folk wisdom was in elite Jacobean culture. It captures a transitional moment when an oral proverb gained theatrical authority, fixed in the dialogue of a major poet-dramatist at the height of his powers. The boundary between the tavern and the theater was never as rigid as we might assume; the pig that could not fly belonged to both.
On top of that, the play’s revival in modern criticism owes something to the striking topicality of its themes. Think about it: in an era of financial bubbles, misinformation campaigns, and cults of personality, Jonson’s portrait of a society that believes whatever serves its ambition feels prophetic. When modern audiences hear the phrase when pigs fly, they are continuing a tradition of skepticism that Jonson’s play helped legitimize on the English stage Small thing, real impact. Practical, not theoretical..
Frequently Asked Questions
Did Ben Jonson invent the phrase “when pigs fly”?
No. The expression predates Jonson and existed in Scottish and English oral tradition as a proverbial shorthand for impossibility. That said, The Devil Is an Ass is one of the earliest and most significant literary works to theatricalize the adage, helping to preserve and popularize it among educated audiences.
What is The Devil Is an Ass actually about?
At its core, the play is a satire about human nature. A minor devil named Pug comes to London expecting easy prey but discovers that human beings are already so adept at fraud and self-interest that he is completely outclassed. The title reflects the irony that the devil, traditionally a figure of terror, is here the fool.
How does the play use the idea of flying pigs?
Jonson deploys the adage to underscore the absurdity of the schemes and delusions that occupy his characters. In a world where people believe in convenient witchcraft and effortless wealth, the proverb reminds the audience that certain things—like airborne swine or honest profit without labor—remain impossible.
Why is the character Pug called an ass?
The title The Devil Is an Ass does not refer solely to Pug. It comments on the entire demonic enterprise as viewed from Earth. In Jonson’s London, evil has become so banal and humans so practiced at it that infernal intervention looks outdated and foolish. The devil is an ass because he is unnecessary.
Conclusion
Nearly four centuries after its first performance, The Devil Is an Ass endures not only as a satirical triumph but as an unexpected archive of the English language’s folk wisdom. Yet Jonson’s use of it was never merely comic. The proverb when pigs fly, already old when Ben Jonson gave it theatrical life in 1616, continues to dismiss absurdity with the same barnyard humor. By placing the impossible image of a flying pig in the same dramatic world as human greed, social pretension, and occult fraud, he taught his audience to recognize a deeper truth: the most dangerous impossibilities are not the ones we laugh at, but the ones we choose to believe.
