Alchemists sought gold in it. David Bowie refrigerated it to ward off evil. In the trenches of Ypres soldiers used it as a gas mask, whereas modern-day terrorists add it to home-made explosives. All the Fullers, Tuckers and Walkers in the phonebook owe their names to it, and in 1969 four bags for storing it were left on the surface of the moon. Bought and sold, traded and transported, even carried to work in jugs, urine has made bread rise, beer foam and given us gunpowder, stained glass, Robin Hood's tights and Vermeer's Girl With A Pearl Earring. And we do produce an awful lot of it. Humans alone make almost enough to replace the entire contents of Loch Lomond every year. Add the incalculable volume contributed by the rest of the animal kingdom and it might soon displace a small ocean. No wonder it gets everywhere. In Life of Pee Sally Magnusson unveils the secret history of civilisation's most unsavoury and unsung hero, and discovers how our urine footprint is just as indelible as our carbon one.