In this groundbreaking new biography, based on more than 10,000 hitherto unavailable letters and diary entries, Niall Ferguson returns to his roots as a financial historian to tell the story of Siegmund Warburg, an extraordinary man whose philosophy of finance was the antithesis of the debt-fuelled, algorithm-driven banking of our own time. A refugee from Hitler's Germany, Warburg rose to become the dominant figure in the post-war City of London and one of the architects of European financial integration. Seared by events in the 1930s, when the long-established Warburg bank was first almost destroyed by the Depression and then 'Aryanized' by the Nazis, Warburg was determined that his own bank would learn from the past and contribute to the economic recovery of Britain, the unity of Western Europe and the birth of globalization. Siegmund Warburg was a complex and ambivalent man, as much a psychologist, politician and actor-manager as a banker. In High Financier Niall Ferguson reveals Warburg's idiosyncracies: the love-hate relationships, the feline intuitions, the mercurial temper-tantrums. But above all he recaptures the meticulous business methods and strict ethical code that set Warburg apart from the mere speculators and traders who inhabit today's financial world.