Philosophy and economics were not simply separate interests of Karl Marx. His philosophy provided the intellectual framework and the very language in which Marx understood economics. That language must be understood in order to understand Marxian economics, regardless of whether or not the economic substance is logically independent. The philosophy is also important in itself as the driving force behind a vision that has come to dominate a major part of the globe and of the human species.
- From Marxism: Philosophy and Economics by Thomas Sowell (1985)