Look closely and the shape resolves into disaster: the German airship Hindenburg tipping nose-down, its tail swallowed by a boiling cloud of flame, the whole catastrophe pinned against a blank cream sky. It is the moment a machine the length of an ocean liner became a fireball, and it sits on the front of Led Zeppelin's 1969 debut with the band's name floating above it in a few plain letters.

Jimmy Page chose the image, and the joke buried inside it is grim: a group whose name mocked the idea of a doomed flying craft put an actual doomed flying craft on their cover. There is no photograph here, only ink, thousands of tiny dots massed into something that looks like a newspaper picture enlarged past the point of clarity.

That single choice, tragedy reprinted as swagger, is what makes the sleeve impossible to file away as decoration. How a burning airship from 1937 ended up baptizing a rock band, who drew it and why, and what the drawing later became, is the rest of the story.