Earlier we met those words and phrases that made no sense to us when we were little and not so little, the “plejallegiance” or the “forgive us our trespasses” of the Lord's prayer. Without checking the gloss on the bottom of the page, few of us know, or remember if we did check, what exactly the image of being hoist with a petar(d) is. When we read Shakespeare we are so often faking reading Shakespeare. Many think the image of petards means being run up a flagpole or tossed in the air and impaled on your own spear (and to justify this the line is often misremembered as hoist on his own petard). Even misunderstood in that way, the metaphor is properly conceived as having something to do with plots recoiling on the plotter in ways he never foresaw, of having himself become the inadvertent object of his own machinations intended to undo another. To be hoist with your own petard really means to have the mine or shell you intend for the enemy explode in your own face.