Muster of the Tribe of Levi. - As Jacob had adopted the two sons of Joseph as his own sons, and thus promoted them to the rank of heads of tribes, the tribe of Levi formed, strictly speaking, the thirteenth tribe of the whole nation, and was excepted from the muster of the twelve tribes who were destined to form the army of Jehovah, because God had chosen it for the service of the sanctuary. Out of this tribe God had not only called Moses to be the deliverer, lawgiver, and leader of His people, but Moses’ brother Aaron, with the sons of the latter, to be the custodians of the sanctuary. And now, lastly, the whole tribe was chosen, in the place of the first-born of all the tribes, to assist the priests in performing the duties of the sanctuary, and was numbered and mustered for this its special calling.