A.C. Pigou spent his career in the shadow of Marshall and Keynes and his contributions have seemed small by comparison, but his influence remains significant. He is regarded by many as the father of modern public finance and welfare theory, as the way that economists analyze and justify government intervention in economic affairs stems from Pigou. Following on from A. C. Pigou’s 1903 pamphlet, The Riddle of the Tariff, this book, originally published in 1906, is a more technical treatment, leaning on the Marshalian apparatus and coming out against the policy of Imperial preference.