Hoist with his own petard  "Hoist with his own petard" is a phrase from a speech in William Shakespeare's play "Hamlet" that has become proverbial. The phrase's meaning is literally that a bomb-maker is blown up ("hoist" off the ground) by his own bomb (a "petard" is a small explosive device), and indicates an ironic reversal, or poetic justice. The phrase occurs in a central speech in the play in which Hamlet has discovered a plot on his life by Claudius and resolves to respond to it by letting the plotter be "Hoist with his own petard". Although the now-proverbial phrase is the best known part of the speech, it and the later sea voyage and pirate attack are central to critical arguments regarding the play. The phrase, and its containing speech, exist in only one of three early printed versions of the play—the second quarto edition—and scholars are divided on whether this is indicative of authorial intent, or a mere artifact of playhouse practicalities. The phrase occurs in "Hamlet" Act 3, Scene 4, as a part of one of Hamlet's speeches in the Closet Scene. Hamlet has been acting mad to throw off suspicion that he is aware that his uncle, Claudius, has murdered his father and married his mother, Queen Gertrude, in order to usurp the throne. In the Closet Scene, Polonius, at Claudius' behest, has hidden himself behind an arras in Gertrude's chambers to listen in as Gertrude scolds Hamlet for his mad antics, hoping to determine whether he is truly mad or merely pretending. On revealing his presence, Hamlet kills him thinking him to be Claudius. Hamlet then accuses Gertrude of complicity in his father's murder, but when she protests her innocence, the two of them begin to conspire to reveal Claudius's guilt. Having previously been ordered to travel to England on a pretext, accompanied by Rosencrantz and Guildenstern carrying letters to the King of England, Hamlet tells his mother:  The letters contain a request from King Claudius to the King of England to have Prince Hamlet killed, but Hamlet manages to modify them during the journey so that they instead request the deaths of Rosencrantz and Guildenstern. Hamlet is thus able to return to Denmark in secret to seek his revenge. "Hamlet" exists in several early versions: the first quarto edition (Q1, 1603), the second quarto (Q2, 1604), and the First Folio (F, 1623).