First, it has to be noted that the differentiation of this order from the rest of society is in primitive communities very incomplete. Fathers of families, or any venerable and respected men, act as priests, and perform the requirements of divine worship according to their own notions of propriety. Thus in Samoa, Mr. Turner tells us that "the father of the family was _the high-priest_, and usually offered a short prayer at the evening meal, that they might all be kept from fines, sickness, war, and death." He also directed on what occasions religious festivals should be held, and it was supposed that the god sometimes spoke through the father or another member of the family (N. Y., p. 239). So in the early period of the history of the Israelites, there was no formal and regular priesthood, and no established ritual. The Levites were not devoted to the functions they subsequently discharged, until, in the course of the Exodus, they had proved their qualification by the holy zeal with which they slaughtered their brethren. It was for the perpetration of this massacre that they were promised by Moses the blessing of God (Exod. xxxii. 25-29). With advancing culture, the necessity for separating priests from laymen is always felt. The ministrations of unskilled hands are not held to be sufficient. Ritual grows fixed; and for a fixed ritual there must be a special apprenticeship. Ceremonies multiply; and the original family prayer having grown into a more elaborate system of worship, takes more time, and demands the attention of a class who make this, and kindred matters, their exclusive occupation.