Calvin's Commentaries, Vol. 4: Harmony of the Law, Part II, tr. by John King, [1847-50], at sacred-texts.com
Deut. 24:8, 9
8. Take heed in the plague of leprosy, that thou observe diligently, and do according to all that the priests the Levites shall teach you: as I commanded them, so ye shall observe to do.
8. Observa in plaga leprae, ad observandum diligenter et faciendum secundum omnia quae docuerint vos sacerdotes Levitae: sicuti praecepi eis, ita observabitis ad faciendum.
9. Remember what the Lord thy God did unto Miriam by the way, after that ye were come forth out of Egypt.
9. Recordare quid fecerit Jehova Deus tuus Mariae in itinere, quum egressi estis ex Aegypto.
8. Take heed in the plague of leprosy. I am aware how greatly interpreters differ from each other and how variously they twist whatever Moses has written about Leprosy. Some are too eagerly devoted to allegories; some think that God, as a prudent Legislator, merely gave a commandment of a sanitary, nature, in order that a contagious disease should not, spread among the people. This notion, however, is very. poor, and almost unmeaning; and is briefly. refuted by Moses himself, both where he recounts the history of Miriam’s leprosy, and also where he assigns the cause why lepers should be put out of the camp, viz that they might not defile the camp in which God dwelt, whilst he ranks them with those that have an issue, and that they are defiled by the dead. Wherefore, I have thought it well, previous to attempting the full elucidation of the matter, to adduce two passages, by way of preface, from whence the design of God may more fully appear. When, in this passage from Deuteronomy, He commands the people to “take heed” and “observe diligently” the plague of leprosy, there can be no question but that He thus ratifies what He had before set forth at greater length in Leviticus. And, first of all, He refers the judgment of the matter to the priests, that what they pronounce should be firm and unalterable; and secondly, He would have the priests, lest they should pronounce rashly, and according to their own wishes, to follow simply what He prescribed to them, so that they may only be the ministers, or heralds; whilst, as to the sovereign authority, He alone should be the Judge. He confirms the law which He imposes by a special example; because He had cast out Miriam, the sister of Moses, for a time, lest her uncleanness during her leprosy should defile the camp. For the view which some take, that He exhorts the people lest, through sin, they should bring upon themselves the same evil as Miriam, is not to the purpose. But that which I have stated makes excellent sense, viz., that God’s command, whereby He prohibited Miriam from entering the camp, was to have the force and weight of a perpetual law; because He thus ordained what He would always have done.