New York’s former Gov. Andrew Cuomo has been “hoist on his own petard,” several news organizations reported recently. Many people use this idiom correctly while being unable to identify quite what the metaphor involves. According to one online dictionary of idioms, it means being “injured ... by one’s own action ... that was intended to harm another; falling victim to one’s own trap or schemes.” In 2019, Mr. Cuomo signed a law that strengthened protections against sexual harassment in the workplace; in 2021, he was forced to resign after 11 employees accused him of sexually harassing them.
But, to quote one of the best language-related headlines, from The Sydney Morning Herald, “What is a petard and how do you get hoist by your own?”
In Modern English, “hoist” would be hoisted – lifted up with much effort, or via a mechanical device such as a pulley. The idiom’s hoist is the past tense of an older verb that is now obsolete: hoise (sometimes spelled and pronounced hyse). This word derives from a simple sea shanty, a song or phrase that sailors would repeat in order to coordinate their actions during a voyage. In the 15th century, sailors would chant “howe, hissa!” to time their pulls on the ropes to raise the sails; eventually hissa transformed into hoise and became a verb for the action whose tempo it had regulated. During the 16th century, its past tense gave rise to the modern hoist/hoisted.
Petards were medieval explosives, square- or bell-shaped devices that contained several pounds of gunpowder, used to blow open doors. An “engineer” – what the military calls a sapper today – would place the petard against a door, light its fuse, and run. This was as dangerous as it sounds: If something went wrong, the engineer would be “hoist” (lifted in the air by the force of the explosion) by the petard he had set.
William Shakespeare gets the credit for first linking petards and hoisting, in 1604’s “Hamlet.” When Hamlet realizes that his uncle has ordered two vassals (Rosencrantz and Guildenstern) to kill him, he pledges instead to turn the tables: “For ’tis the sport to have the engineer / Hoist with his own petard.” Hamlet says “with,” and “by” also makes sense. Frequently today, though, it appears as “hoist on one’s own petard.”
Historian William Ian Miller attributes this new preposition to the fact that so few people are familiar with these old and specialized words. Even when reading “Hamlet,” Mr. Miller argues, it’s easy to think that the metaphor has something to do with “being run up a flagpole, or being tossed in the air and impaled on your own spear,” in which case “hoist on” does indeed work.