In every early religion there will of course be found, apart from external influence, traces of its own internal development, of stages by which it must have advanced from a mass of vague and primitive belief and custom to the organised worship of a civilised community. The religion of Rome is no exception to this rule; we can detect in its later practice evidences of primitive notions and habits which it had in common with other semi-barbarous peoples, and we shall see that the leading idea in its theology is but a characteristically Roman development of a marked feature in most early religions.