We're marking the birth of William Shakespeare (on or around this date in 1564) with a look at a Shakespearean phrase. (来源：英语学习门户 http://www.EnglishCN.com)

In Act Three of Hamlet, Shakespeare has his melancholy Prince muse: "For 'tis the sport to have the engineer/Hoist with his own petar." These days, we know hoist with or by one's own petard as a metaphor for "victimized or hurt by one's own scheme;" in those days, the term was more literal.

Hoise is the dialectal form of hoist and hoist is its inflected form, meaning "to raise into position by, or as if by means of tackle."

So what's a petard? A case shaped like a bell or a bucket crammed full of gunpowder and secured shut with a slab of wood. Petards were handy during sieges, when petardiers (the engineers) would quietly haul up—or hoist—their explosive device to the gate of the palace or fortress and lean the petard against it, wooden lid side to the gate. The petardiers would then light a fuse on the bomb and run like crazy lest the force of the explosion shoot out shrapnel in their direction.

Thus, woe betide the slow-moving petardier who might be hoist by his own petard. But whence petard? Thank (or blame) the French. The French ancestor of petard gave them both the verb meaning "to break wind" and the noun meaning "the report of a firearm." But the bawdy Bard let loose with the phrasing that appealed to his audience.