Eleazar and Ithamar "ministered in the priest's office in the presence of Aaron their father." So far as the narrative of the Pentateuch gives information, there were originally, and during the whole of the wilderness journey, no other priests than Aaron and his sons. Nadab and Abihu having died, there remained but the two besides their father. Phinehas the son of Eleazar appears in the history, but is not called a priest, nor has he any priestly functions. What he does is indeed quite apart from the holy office. And this early restriction of the number is not only in favour of the Pentateuchal history, but partly explains the fact that in Deuteronomy the priests and Levites are apparently identified. Taking at their very heaviest the duties specially laid on the priests, much must have fallen to the share of their assistants, who had their own consecration as ministers of the sanctuary. It is certain that members of the Levitical families were in course of time admitted to the full status of priests.
The direction is given in ver. 10, "Thou shalt appoint Aaron and his sons, and they shall keep their priesthood; and the stranger that cometh nigh shall be put to death." This is rigorously exclusive, and seems to contrast with the statements of Deuteronomy, "At that time the Lord separated the tribe of Levi to bear the ark of the covenant of the Lord, to stand before the Lord to minister unto Him and to _bless in His name_ unto this day" (x. 8); and again, "The priests the Levites, even all the tribe of Levi, shall have no portion nor inheritance with Israel; they shall eat the offerings of the Lord made by fire, and His inheritance" (xviii. 1); and once more, "Moses wrote the law and delivered it unto the priests, the sons of Levi, which bore the ark of the covenant of the Lord, and unto all the elders of Israel" (xxxi. 9). Throughout Deuteronomy the priests are never called sons of Aaron, nor is Aaron called a priest. Whether the cause of this apparent discrepancy is that Deuteronomy regarded the arrangements for the priestly service in a different light, or that the distinction of priests from Levites fell into abeyance and was afterwards revived, the variation cannot be ignored. In the book of Joshua "the children of Aaron the priest" appear on a few occasions, and certain of the duties of high priest are ascribed to Eleazar. Yet even in Joshua the importance attached to the Aaronic house is far less than in Exodus, Leviticus, and Numbers; and the expression "the priests the Levites" occurs twice. If we regard the origin of the Aaronic priesthood as belonging to the Mosaic period, then the wars and disturbances of the settlement in Canaan must have entirely disorganised the system originally instituted. In the days of the judges there seems to have been no orderly observance of those laws which gave the priesthood importance. Scattered Levites had to do as they best could what was possible in the way of sacrifice and purification. And this confusion may have begun in the plain of Moab. The death of Aaron, the personal insignificance of his sons, and still more the death of Moses himself, would place the administration of religious as well as secular affairs on an entirely different footing. Memoranda preserved in Leviticus and Numbers may therefore be more ancient than those of Deuteronomy; and Deuteronomy, describing the state of things before the passage of Jordan, may in regard to the priesthood reflect the conditions of a new development, the course of which did not blend with the original design till after the captivity.