Economics, from its establishment to a thriving economic jungle, needs to be sorted out in its system. Through research on Locke’s state theory of nature, we found the inherent relationship between the emergence and development of economics and this theory. Natural identity of the interest in the natural state theory is the premise of the establishment of economics and is also the basis of the continuous evolution of mainstream economics. Meanwhile, Locke’s state theory of nature ignores the conflict of interests between people, so Hobbes problems are appeared in the form of one kind or another in nonmainstream economics and constitute another pole in the theoretical system of economics. Identity and contradiction of interest constitute the internal logic of the evolution of economics. Based on above views, the author rearranges the family tree of economics.