Deuteronomy 33:9

9.Who said unto his father and his mother. In the person of Aaron an example is set before all the Levites for their imitation. And, first, he is said to have renounced his own flesh and blood, in order that he might be more disencumbered for obeying God; and in fact it is necessary that all the pastors of the Church should put off their earthly affections, which would otherwise often keep them back from devoting themselves entirely to God. Aaron, then, is said to have bid farewell to all his family, that he might be at liberty to lay himself out for God. Christ now requires the same thing of His disciples, that sons should forget their fathers, and fathers their sons, and husbands their wives, lest anything should retard their course, and prevent them from earnestly advancing through life and death to the end to which they are called. (Matthew 10:37.)

Moses afterwards, by using the plural number, embraces the whole Levitical order; and hence we may infer that what had preceded is not to be confined in its application to a single individual. But when he says that they “guarded(custodisse) the word of God, and kept his covenant,” he does not refer to mere ordinary obedience, but to the peculiar care of preserving that which was intrusted to their charge. It is true that in like manner all believers are said to keep the Law, when they zealously devote themselves to live a holy life; but special allusion is here made to the office of teaching. The Levites, therefore, are called guardians of the Law, and keepers of it, as being φύλακες , since with them was deposited the treasure of Divine instruction, as is more clearly set forth in the next verse, “They shall teach Jacob, etc.” If any should prefer that this observing of the Law should be understood of their life and habits, as though it were said, that the Levites should surpass others in the examples they gave, I do not contend the point, though it seems to me that the second clause is explanatory, and that it more familiarly sets forth what was spoken with some little obscurity, pointing out the way in which the Law is to be observed, viz., by their being the teachers and masters of the people. We must, however, remark the method they are to adopt in teaching; for they are not permitted to introduce their own inventions, or to frame a rule of life out of their own heads; but they are commanded to seek in the Law itself what they are to teach, and to interpret it honestly and faithfully. And this condition was inserted in order that whosoever should desire to be successors in the honor should be mindful of their vocation, and faithfully devote themselves to the office of teaching. Thus, when in a corrupt state of the Church, priests, who had nothing of this sort about them, paraded their mere empty title; their silly vaunt is refuted by Malachi:

“My covenant (he says) was with Levi of life and peace;.... for the law of truth was in his mouth, and the priest’s lips should keep knowledge, and they should seek the law at his mouth, but ye have corrupted my covenant,” (Malachi 2:5.)

Let us learn, then, from this passage, that whosoever claims for himself the primacy in the Church must be repudiated, unless he manifests himself to be a faithful teacher.

The third part of the priest’s office follows, viz., that he should apply himself to the performance of the religious services; for God had disencumbered them from the labors of agriculture and other earthly business, that they might be more entirely at liberty for the duties of teaching and sacrifice; and, although this latter might appear to be but an humble occupation, still, if we regard it aright, it was no common honor that they should be mediators and intercessors for the reconciliation of the people to God; for even the very least of the Levites had something to do with making atonement.

Under the words “incense and whole burnt-sacrifice,” the entire legal service is comprehended; and the incense is said to be put before the nose of God; (316) because the odor of this offering was grateful, and, as it were, sweet-smelling to Him, as we have elsewhere seen.