Questions about the relationship between equity and growth, which lie at the heart of every chapter in this volume, are at least as old as economics itself. In the preface to his On the Principles of Political Economy and Taxation, David Ricardo wrote: "The produce of earth—all that is derived from its surface by the united application of labor, machinery and capital—is divided among three classes of the community, namely the proprietor of the land, the owner of the stock or capital necessary for its cultivation, and the laborers by whose industry it is cultivated. But in different stages of society, the proportions of the whole produce of the earth which will be allotted to each of these classes ... will be essentially different ... To determine the laws which regulate this distribution is the principal problem in Political Economy."