250 THE AMERICAN JOURNAL OF SOCIOLOGY
that they are by nature our fellow-men, our brothers, the descendants of God."
Thus the conception of a natural and universal human law was introduced in the Roman world at the same time that its interior limits were being broken in order to reach out over the most assimilated parts of the three known continents.
The monogenism of the human species was then conceived as an ideal and of divine origin. The parallel evolution of the doctrine with the historic evolution of society was not even caught sight of ; the unity of the human species had its origin in the unity of the God of the universe. The idealistic and super- natural conception formulated itself in Christianity through the divorce of the spiritual and temporal a divorce which the Catholic Middle Ages extended to the two corresponding powers. The idea is separated from the fact. All men are equal and brothers in God. Among them there are no inequalities, no barriers before the Creator; but said Jesus: "My kingdom is not of this world ;" " Render to Caesar that which is Caesar's and to God that which is God's." That is to say, pay to Caesar the tribute, symbol of political submission. The Christian equality is extra-mundane, neither political nor social. It is, however, voluntarily possible here below, if the great consent to be little.
Let us remark, however, that henceforth the abolition of frontiers among classes and societies is conceived of as one of the essential aspects of equality. It was, indeed, one of the his- toric functions of frontiers to maintain among men and peoples at least an external equilibrium effected by restrictions and pro- hibitions, i. e., by exterior constraint, awaiting their internal social equilibrium.
We know that the separation and relative limits of the spiritual and temporal, were the great problems of the Middle Ages. The separation still forms a part of the heavy debt of our heritage, and its dualism will finally resolve itself only into the monistic conception of society a conception already pre- pared by the psycho-physiological monism which is slowly but inevitably being substituted for this corresponding dualism of mind and body.
