3:15 From a month old - Because at that time the first - born, in whose stead the Levites came, were offered to God. And from that time the Levites were consecrated to God, and were, as soon as capable, instructed in their work. Elsewhere they are numbered from twenty - five years old, when they were entered as novices into part of their work, Num 8:24, and from thirty years old, when they were admitted to their whole office.
3:14-39 The Levites were in three classes, according to the sons of Levi; Gershon, Kohath, and Merari; and these were subdivided into families. The posterity of Moses were not at all honoured or privileged, but stood upon the level with other Levites; thus it was plain, that Moses did not seek the advancement of his own family, or to secure any honours to it. The tribe of Levi was by much the least of all the tribes. God's chosen are but a little flock in comparison with the world.
