Family, which is a construction based on and controlled by natural powers in the ancient times, is the basic unit of classical society. From the point of view of Christianity, Augustine dissociates the individual from secular communities and restores him to a purely spiritual entity, so as to establish a starting point for the Christian model of society. Meanwhile, the classical family, as the basic organizational form of community, is deconstructed by Augustine through denaturing its natural power. Augustine denies the virtuous and ultimate meaning of any secular communities. As a result, Augustine understands human society, in the framework of Christianity, as a "societas" based on the principle of equality and love. In this metaphysical society, marriage is established and sanctified on the same principle of equality and love, and so the hallowed marriage contract becomes the smallest basic organizational form of human society, instead of family in ancient times. Augustine thus creates a brand new model of society based on the marriage contract as its basic unit. Although this new model occupied the dominant position in medieval Europe, it has always had an inner tension between the ideal and the reality. With the collapse of Feudalism and Catholicism, this model began to disintegrate, but the principle of equality, love and contract remains. The Renaissance, the Reformation and the Enlightenment together emancipated the individual from the religious community and established the modern idea of individual as capable and deserving of "liberty and reason". On this basis, modern thinkers such as Hobbes and Hegel introduced the principle of equality, love and marriage contract as the organizational logic of the family, and then of the society. By this way, modern thinkers form a complete chain that starts from the atomic individual and ends with the whole of society so as to establish an entirely new pattern for the organization of human society. The family of this new type i.e., the "core family" based on the marriage system as T nnies and Durkheim suggest, becomes the basic unit of modern society.