W.H. Auden called Harry Kessler the most cosmopolitan man who ever lived. Aesthete, patron, diplomat, diarist, peace campaigner, defender of the Weimar republic and exile from Nazism, this ultra-sophisticated German count belongs to a type that probably no longer exists: a moneyed and cultivated amateur whose brains and background brought him effortless access to politics, society and intellectual life in any capital where he set foot.