The explanation is to be found in the state of the human mind during these centuries. The Middle Ages were essentially unpolitical. Ideas as familiar to the commonwealths of antiquity as to ourselves, ideas of the common good as the object of the State, of the rights of the people, of the comparative merits of different forms of government, were to them, though sometimes carried out in fact, in their speculative form unknown, perhaps incomprehensible. Feudalism was the one great institution to which those times gave birth, and feudalism was a social and a legal system, only indirectly and by consequence a political one. Yet the human mind, so far from being idle, was in certain directions never more active; nor was it possible for it to remain without general conceptions regarding the relation of men to each other in this world. Such conceptions were neither made an expression of the actual present condition of things nor drawn from an induction of the past; they were partly inherited from the system that had preceded, partly evolved from the principles of that metaphysical theology which was ripening into scholasticism[102]. Now the two great ideas which expiring antiquity bequeathed to the ages that followed were those of a World-Monarchy and a World-Religion. [Sidenote: The World-Religion.] Before the conquests of Rome, men, with little knowledge of each other, with no experience of wide political union[103], had held differences of race to be natural and irremovable barriers. Similarly, religion appeared to them a matter purely local and national; and as there were gods of the hills and gods of the valleys, of the land and of the sea, so each tribe rejoiced in its peculiar deities, looking on the natives of another country who worshipped other gods as Gentiles, natural foes, unclean beings. Such feelings, if keenest in the East, frequently shew themselves in the early records of Greece and Italy: in Homer the hero who wanders over the unfruitful sea glories in sacking the cities of the stranger[104]; the primitive Latins have the same word for a foreigner and an enemy: the exclusive systems of Egypt, Hindostan, China, are only more vehement expressions of the belief which made Athenian philosophers look on a state of war between Greeks and barbarians as natural[105], and defend slavery on the same ground of the original diversity of the races that rule and the races that serve. The Roman dominion giving to many nations a common speech and law, smote this feeling on its political side; Christianity more effectually banished it from the soul by substituting for the variety of local pantheons the belief in one God, before whom all men are equal[106]. [Sidenote: Coincides with the World-Empire.]