In this book, originally published in 1937, Jacob Viner traces, in a series of studies of contemporary source-material, the evolution of the modern orthodox theory of international trade from its beginnings in the revolt against English mercantilism in the 17^th and 18^th centuries, through the English currency and tariff controversies of the 19^th century, to the late 20^th century. The author offers a detailed examination of controversies in the technical literature centering on important propositions of the classical and neo-classical economists relating to the theory of the mechanism of international trade and the theory of gain from trade.