The film It Might Get Loud (2008) throws Jimmy Page, Jack White, and a man who willingly goes by The Edge onto a bare soundstage with nothing but stories and amplifiers. In a scene, Page straps on his battered Danelectro and uncoils "Kashmir." The Edge, wide-eyed, asks where that rhythm came from, that strange pulse. Page grins and says it was born from fooling around in DADGAD, a tuning that bends toward the sitar. He had been sketching a piece called "Swan Song," dense and layered, when the bones of "Kashmir" surfaced at Headley Grange with Bonham pounding it into the earth. He calls it a hypnotic riff, circling, cascading, brushing against dissonance until you lose yourself. Three generations of guitar heroes stand there trading secrets like contraband and letting the noise echo in the void.