which induced several tribes to unite; what is certain is that the bond of the new association was again a religion. The tribes which grouped themselves to form a state never failed to light a sacred fire, and to set up a common religion." But the family and tribal rites continued to exist as _sacra privata_, just as the central government dominated but did not destroy the family and tribal governments.[88] [88] Cf. also Muirhead, article "Roman Law," in _Ency. Brit._, vol. xx. p. 669, 2nd col., and Ramsay, _Church in Roman Empire_, p. 190. It may be objected that these customs are proved only for the Aryan races, and that, though proved for them, they form no valid analogy for Semitic peoples. But besides the fact that part of the statements we have quoted are obviously true of Israel, we have a guarantee that the principle enunciated is also valid for it. The whole process traced in the religious progress of the Aryan nations is based upon the worship of ancestors. Now one of the critical discoveries is that ancestor-worship was a part of the religion of the tribes which afterwards united to form the Israelite nation. Some, like Stade, tell us that that was the early religion of Israel itself. In that form the theory is, I think, to be rejected; but there would seem to be little doubt that, before the birth of the nation, ancestor-worship was much practised by the Hebrew tribes. If so, we may quite safely take over the analogy we have established, and believe that when Moses united the tribes into a nation, the religion of Yahweh was the absolutely necessary connecting link which bound them together. For though the tribes were related, and are represented as the descendants of Abraham, they must have varied considerably from each other in religious beliefs and usages. By Moses these variations were extinguished, as far as that was possible, by the establishment of an exclusive Yahweh-worship as the national cult; and to carry on this, not the heads of households, but a priesthood that represented the nation, must have been selected. But if so, who would most naturally be selected for this duty? A sentence from De Coulanges will show that in this case the tribe of Levi would almost necessarily be chosen. Speaking of cases in which a composite state relieved itself of the trouble of inventing a new worship by adopting the special god of one of the component tribes, he says: "But when a family consented to share its god in this fashion it reserved for itself at least the priesthood." Now if that was the case in Israel, the priesthood of the tribe of Levi would at once become a necessity. Whether Yahweh had been ever known to the other tribes or not, there can be little doubt that the knowledge of Him which made them a nation and started them on their unique career of spiritual discovery came from the Mosaic tribe, and family.