The book explains the past history and present state of Walrasian general economic equilibrium theory, which incorporates most of microeconomic theory. The treatment examines the foundations of the legacy of Leon Walras, the originator of general equilibrium theory, and his influence as manifested in the work of his successors. It is shown that he initiated strains of theorizing and a research agenda that have dominated the course of microeconomic theory even more than is currently appreciated.