Q: I’ve always thought that one was “hoist on” one’s own petard, but I recently saw it as “hoist by” one’s own petard. I think “on” makes sense and “by” doesn’t.
A: When Shakespeare coined the expression in Hamlet more than 400 years ago, he used the preposition “with.” Online standard dictionaries now include “by” as well as “with.” Both of those make sense to us, though “on” does not.
Merriam-Webster, for example, calls its entry “hoist with one’s own petard or hoist by one’s own petard,” and defines the usage this way: “victimized or hurt by one’s own scheme.” Lexico (the former Oxford Dictionaries Online) and American Heritage also include both prepositions.
The Oxford English Dictionary, an etymological dictionary based on historical evidence, defines the expression as meaning “blown into the air by his own bomb; hence, injured or destroyed by his own device for the ruin of others.”
The OED says the usage originated in Act III, Scene 4 of Hamlet (probably written between 1599 and 1602). Hamlet uses it when he speaks of foiling the efforts of Rosencrantz and Guildenstern to betray him: “Tis the sport to haue the enginer / Hoist with his owne petar.”
The word “hoist” here is a past tense and past participle of the old verb “hoise.” When this verb first appeared as a nautical term in the late 15th century, to “hoise” meant to “raise aloft by means of a rope or pulley and tackle, or by other mechanical appliance,” the OED says.
Here’s an example from William Caxton’s 1490 translation of Virgil’s Aeneid: “They made the saylles to be hyssed vppe.”
The modern verb “hoist” appeared in the mid-16th century as a corruption of “hoise.” The OED’s first example is from an English translation, overseen by Nicholas Udall, of Erasmus’s Latin paraphrase, or retelling, of the New Testament: “His onely soonne they hoihsted vp and nayled on the crosse.”
The verb “hoise,” which the OED describes as obsolete or dialectal, had two different past tenses and past participles: “hoised” and “hoist.”
When Shakespeare used “hoist” in Hamlet, the raising was done by a “petard,” which Oxford describes as a small bomb made of a metal or wooden box filled with powder, used to blow in a door, gate, etc., or to make a hole in a wall. Now historical.”
The earliest Oxford citation for “petard” is from an obscure 1566 entry in the accounts of the lord high treasurer of Scotland. The next cite is clearer:
“A squib or petard of gun powder vsed to burst vp gates or doores with” (from A Worlde of Wordes, 1598, an Italian-English dictionary by John Florio).