Does anyone know where the saying, 'hoist by his own petard' means? And where it comes from?
The French word pétard means a loud discharge of intestinal gas, - not silent but deadly but a big ole noisy bi-labial fricative. To be hoist by one's own petard, is a now proverbial phrase apparently originating with Shakespeare's Hamlet (around 1604) not long after the word entered English (around 1598). It means to blow oneself up with one's own bomb, be undone by one's own devices. The French developed a kind of infernal engine, named the Petard, only about a decade before Shakespeare used the hoisting phrase in Hamlet, for blasting through the gates of a city. The French noun pet, fart, developed regularly from the Latin noun pēditum, from the Indo-European root *pezd-, fart. During WWII, the British had a munition also called the Flying Dustbin. which was a spigot mortar. It fired a 40-pound (18 kg) finned bomb at pillboxes and other concrete obstacles, to destroy them - but that was long after Hamlet was published.
The word remains in modern usage in the phrase to be hoisted by one's own petard, which means to be harmed by one's own plan to harm someone else or to fall in one's own trap. Shakespeare coined the now proverbial phrase in Hamlet.
Garrett B is correct. The petard was shaped rather like an elongated bell. The bell part was thick and strong, and there was a thinner sheet across the mouth, to hold in the explosive. The engineer had to fix it with the flat mouth against a door or gate. When it exploded, the bell part helped most of the explosion to be directed against the door. Yes, they were unstable, and if it went off too soon the engineer would usually be thrown into the air by the explosion - looking like something was hoisting him.
Hoisted By Your Own Petard
Hamlet: For ’tis the sport to have the enginer Hoist with his own petar; 'The Tragedy of Hamlet, Prince of Denmark.' Act III, Scene IV, lines 224-5. Hamlet was refering to his school-mates Rosencrantz and Guildenstern, who had headed off to England with a letter they thought contained execution orders for Hamlet, but for which he had substituted one ordering their own execution. Thus, 'hoist on his own petard' means caught in his own trap, involved in the danger he meant for others. The petard was a conical instrument of war employed at one time for blowing open gates with gunpowder. The engineers used to carry the petard to the place they intended to blow up, and fire it at the small end by a fusee.
