Melvyn Bragg examines the science of taxonomy. The Argentinean author Jose Luis Borges illustrated the problematic nature of scientific classification when he quoted from an ancient Chinese Encyclopaedia, the Celestial Emporium of Benevolent Knowledge. On these remote pages, in a complete absence of Phylum, Genus and Species, animals are divided into: (a) those that belong to the Emperor, (b) embalmed ones, (c) those that are trained, (d) suckling pigs and those that tremble as if they were mad ending with those drawn with a very fine camel's hair brush , others , those that have just broken the flower vase and those that at a distance resemble flies. Perhaps our own system of classifying the natural world might seem just as fantastical to a more knowing mind, and perhaps underlying the Linnaean system that homo sapiens currently finds useful there are prejudices of our own which distort the scientific truth. How does natural history classify the natural order ?With Colin Tudge, writer, scientist and author of The Variety of Life: A Survey and a Celebration of all the Creatures that Have Ever Lived; Dr Sandy Knapp, Research Botanist, Department of Botany, Natural History Museum, London; Henry Gee, Senior Editor of Nature and author of Deep Time: Cladistics, the Revolution in Evolution.