This book articulates a unified theory of capitalism as an attempt to provide a comprehensive scientific theory of this social system. A unified theory of capitalism is not the combination of the predominant economic theories--neoclassical, classical, and Keynesian--so as to make them compatible. It is not a composite economic theory. It is a new economic theory. Predictions of the theory's models were consistent with eight basic empirical regularities of capitalism dealing with economic growth, income inequality, employment level, and environment degradation. Therefore, the unified theory can be accepted as a good approximation of the real capitalist world. But the models were constructed at a high level of abstraction. Also problematic was the need to work out more fully the public policy implications of the theory. It is, therefore, no wonder that essays on the unified theory to answer these questions are a natural outcome of a new scientific endeavor attempting to reach a unity of knowledge in economics.