The expression "when pigs fly" is often used to indicate that something is extremely unlikely or impossible. It is commonly thought to have originated from various similar expressions used throughout history.

While the phrase has often been attributed to earlier playwrights or writers, there is no definitive evidence that it was first recorded in Ben Jonson's works in 1616. This expression may have evolved from other idiomatic phrases or proverbs that convey the same notion of impossibility, but a distinct origin specifically pointing to Jonson's play has not been validated.

Therefore, while Ben Jonson's works from 1616 might discuss similar themes or expressions, the specific phrase "when pigs fly" does not necessarily trace back to that play as its first recorded use. The exploration of idioms and their origins can often lead to ambiguities, and it is crucial to reference various historical texts for clarity.