11-13. I have taken the Levites, &c.—The consecration of this tribe did not originate in the legislative wisdom of Moses, but in the special appointment of God, who chose them as substitutes for the first-born. By an appointment made in memory of the last solemn judgment on Egypt (from which the Israelitish households were miraculously exempt) all the first-born were consecrated to God (Ex 13:12; 22:29), who thus, under peculiar circumstances, seemed to adopt the patriarchal usage of appointing the oldest to act as the priest of the family. But the privilege of redemption that was allowed the first-born opened the way for a change; and accordingly, on the full organization of the Mosaic economy, the administration of sacred things formerly committed to the first-born was transferred from them to the Levites, who received that honor partly as a tribute to Moses and Aaron, partly because this tribe had distinguished themselves by their zeal in the affair of the golden calf (Ex 32:29), and also because, being the smallest of the tribes, they could ill find suitable employment and support in the work. (See on De 33:8). The designation of a special class for the sacred offices of religion was a wise arrangement; for, on their settlement in Canaan, the people would be so occupied that they might not be at leisure to wait on the service of the sanctuary, and sacred things might, from various causes, fall into neglect. But the appointment of an entire tribe to the divine service ensured the regular performance of the rites of religion. The subsequent portion of the chapter relates to the formal substitution of this tribe.

     40-51. Number all the first-born of the males of the children of Israel, &c.—The principle on which the enumeration of the Levites had been made was now to be applied to the other tribes. The number of their male children, from a month old and upward, was to be reckoned, in order that a comparison might be instituted with that of the Levites, for the formal adoption of the latter as substitutes for the first-born. The Levites, amounting to twenty-two thousand, were given in exchange for an equal number of the first-born from the other tribes, leaving an excess of two hundred seventy-three; and as there were no substitutes for these, they were redeemed at the rate of five shekels for each (Nu 18:15, 16). Every Israelite would naturally wish that his son might be redeemed by a Levite without the payment of this tax, and yet some would have to incur the expense, for there were not Levites enough to make an equal exchange. Jewish writers say the matter was determined by lot, in this manner: Moses put into an urn twenty-two thousand pieces of parchment, on each of which he wrote "a son of Levi," and two hundred seventy-three more, containing the words, "five shekels." These being shaken, he ordered each of the first-born to put in his hand and take out a slip. If it contained the first inscription, the boy was redeemed by a Levite; if the latter, the parent had to pay. The ransom-money, which, reckoning the shekel at half a crown, would amount to 12s. 6d. each, was appropriated to the use of the sanctuary. The excess of the general over the Levitical first-born is so small, that the only way of accounting for it is, by supposing those first-born only were counted as were males remaining in their parents' household, or that those first-born only were numbered which had been born since the departure from Egypt, when God claimed all the first-born as his special property.

     18. Another motive to reverential, vigilant fear (1Pe 1:17) of displeasing God, the consideration of the costly price of our redemption from sin. Observe, it is we who are bought by the blood of Christ, not heaven. The blood of Christ is not in Scripture said to buy heaven for us: heaven is the "inheritance" (1Pe 1:4) given to us as sons, by the promise of God.