There is not a great deal to be said about economics which is truly universal. One can say that economics is the study of economic systems. Economic systems can be defined as systems of human actions concerned with the production and the distribution of goods and services which are scarce relative to the wants of the community. But statements of this kind, which attempt to define the economic aspect of human society in universally valid terms, are far too general to serve as premises from which an economic theory, useful for understanding actual economic problems, can be logically deduced. To have theory, one must start with premises and assumptions about some particular economic system, historically given, or some particular kind of economic system. The great bodies of economic thought of the Western world—mercantilism, classical and neo-classical economic liberalism, and the various schools of Marxist economic—have been theories relevant to particular economic systems: those, let us say, of the Western world in the seventeenth, eighteenth, and nineteenth centuries.