John Calvin Commentary Hebrews 7:16

"who hath been made, not after the law of a carnal commandment, but after the power of an endless life:" — Hebrews 7:16 (ASV)

Carnal commandment, etc. It was called carnal because it refers to physical things, that is, to external rites. We know how Aaron and his sons were initiated into their office. What was fulfilled in Christ by the hidden and celestial power of the Spirit was foreshadowed under the Law by ointment, various vestments, the sprinkling of blood, and other earthly ceremonies. Now this kind of institution was suitable to the nature of the priesthood; it therefore follows that the priesthood itself was liable to change. At the same time, as we will see later, the priesthood was not so carnal as to prevent it from also being spiritual; but the Apostle here refers only to the difference between Christ and Aaron. However spiritual, then, the meaning of these shadows might have been, they were still only shadows in themselves; and as they were made up of the elements of this world, they may justly be called earthly.

After the power of an endless life, or, of an indissoluble life. As Christ is a perpetual priest, it was necessary that he should be different from Aaron regarding the manner of his appointment. And so it was, for it was not Moses, a mortal man, who consecrated him, but the Holy Spirit; and this consecration was not with oil, nor with the blood of goats, nor with the outward pomp of vestments, but with celestial power, which the Apostle here contrasts with weak elements. Thus, we see how the eternity of his priesthood was exhibited in Christ.