John Calvin Commentary Numbers 3:5

"And Jehovah spake unto Moses, saying," — Numbers 3:5 (ASV)

And the Lord spoke to Moses. This passage contains two main points:

1. First, that the Levites should be set apart for the ministry of the sanctuary and altar.
2. Secondly, that they should obey the chief priests of the family of Aaron, and do nothing except by their authority and command.

But it has already been said, and we shall later see again, that the tribe of Levi in general was divinely chosen to perform the sacred offices, so that the people might know that no one was worthy of so honorable a charge, but that it depended on the gracious calling of God, whose attribute it is to create all things out of nothing.

In this way, not only was the rashness of those repressed who might be foolishly ambitious of the honor, but the whole Church was taught that, in order to worship God rightly, there was need of external aid.

For, if the Levites had not stood between, the Law prohibited the rest of the people from having access to God, since it declared the whole human race guilty of pollution.

But, so that they might be more certainly directed to the one Mediator, the high priesthood was exalted, and one priest was chosen to preside over all the rest. For this reason, God ordained that the Levites be subject to the successors of Aaron. At the same time, He also considered order, for a multitude not governed by leaders will always be disorderly.

Yet, it is unquestionable that the supreme power of Christ was represented in the person of Aaron. Thus, the folly of the Papists is refuted, who transfer, or rather distort, this example to the state of the Christian Church,¹⁸⁰ so as to set the bishops over the presbyters and thus invent the primacy of the Roman See.

But if the true meaning of this figure is sought, it will be more appropriate to reason that whatever ministers and pastors of the Church are now appointed, they are placed, as it were, under the hand of Christ, so that they may usurp no dominion but behave themselves modestly, as having to give an account to Him who is the Prince of pastors (1 Peter 5:4).

Therefore, we conclude that the Papacy is founded only on wicked sacrilege, for Christ is unjustly deprived of His own if anyone else is falsely claimed to be Aaron’s successor.

Meanwhile, the political distinction of ranks is not to be rejected, for natural reason itself dictates this to prevent confusion. But such a distinction, having this purpose, will be so arranged that it may neither obscure Christ’s glory, nor serve ambition or tyranny, nor prevent all ministers from fostering mutual fellowship with each other, with equal rights and liberties.

From this also comes the Apostle's declaration, that it is not lawful for any man to take this honor upon himself, but that they are the legitimate ministers of the Church who are “called” to be so (Hebrews 5:4).

¹⁸⁰ “Lesquels partissent tellement l’ordre de leur Hierarchyie qu’en la fin ils parvienent a la primaute du Siege Romain;” who so divide the order of their Hierarchy, that at length they arrive at the primacy of the See of Rome — ;” who so divide the order of their Hierarchy, that at length they arrive at the primacy of the See of Rome — Fr..