It was in accordance with this primitive theory of things that the earliest form of religious worship was developed. In all races of men, so far as can be determined, this was the worship of ancestors.[7] The other self of the dead chieftain continued after death to watch over the interests of the tribe, to defend it against the attacks of enemies, to reward brave warriors, and to punish traitors and cowards. His favour must be propitiated with ceremonies like those in which a subject does homage to a living ruler. If offended by neglect or irreverent treatment, defeat in battle, damage by flood or fire, visitations of famine or pestilence, were interpreted as marks of his anger. Thus the spirits animating the forces of nature were often identified with the ghosts of ancestors, and mythology is filled with traces of the confusion. In the Vedic religion the _pitris_, or "fathers," live in the sky along with Yama, the original _pitri_ of mankind: they are very busy with the weather; they send down rain to refresh the thirsty earth, or anon parch the fields till the crops perish of drought; and they rush along in the roaring tempest, like the weird host of the wild huntsman Wodan. To the ancient Greek the blue sky Uranos was the father of gods and men, and throughout antiquity this mingling of ancestor-worship with nature-worship was general. With the systematic development of ethnic religions, in some instances ancestor-worship remained dominant, as with the Chinese, the Japanese, and the Romans; in others, a polytheism based upon nature-worship acquired supremacy, as with the Hindus and Greeks, and our own Teutonic forefathers. The great divinities of the Hellenic pantheon are all personifications of physical phenomena. At a comparatively late date the Roman adopted these divinities and paid to them a fashionable and literary homage, but his solemn and heartfelt rites were those with which he worshipped the _lares_ and _penates_ in the privacy of his home. His hospitable treatment of the gods of a vanquished people was the symptom of a commingling of the various local religions of antiquity which insured their mutual destruction and prepared the way for their absorption into a far grander and truer system.[8] IV. _Development of Monotheism._