Hebrews 7:11-14
“If therefore perfection were by the Levitical priesthood; (for under it the people have received the law?' ) what further need was there that another priest should arise after the order of Melchisedec, and not be called after the order of Aaron? For the priesthood being changed, there is made of necessity a change also of the law. For He of whom these things are spoken, pertained to another tribe, of which no man gave attendance at the altar. For it is evident that our Lord sprang out of Judah, of which tribe Moses spoke nothing concerning priests.”
1. “If therefore” (he says) “perfection were by the Levitical priesthood.” Having spoken concerning Melchisedec, and shown how much superior he was to Abraham, and having set forth the great difference between them, he begins from this point forward to prove the wide difference as to the covenant itself, and how the one is imperfect and the other perfect. However he does not even yet enter on the matters themselves, but first contends on the ground of the priesthood, and the tabernacle. For these things would be more easily received by the unbelieving, when the proof was derived from things already allowed, and believed.
He had shown that Melchisedec was greatly superior both to Levi and to Abraham, being to them in the rank of the priests. Again he argues from a different point. What then is this? Why (he says) did he not say, “after the order of Aaron”? And observe, I pray you, the great superiority [of his argument]. For from the very circumstance which naturally excluded His priesthood, viz. that He was not “after the order of Aaron,” from that he establishes Him, and excludes the others. For this is the very thing that I say (he declares); why has He “not been made after the order of Aaron”?
And the [saying] “what further need” has much emphasis. For if Christ had been “after the order of Melchisedec” according to the flesh, and then afterwards the law had been introduced, and all that pertained to Aaron, one might reasonably say that the latter as being more perfect, annulled the former, seeing that it had come in after it. But if Christ comes later, and takes a different type, as that of His priesthood, it is evident that it is because those were imperfect. For (he would say) let us suppose for argument's sake, that all has been fulfilled, and that there is nothing imperfect in the priesthood. “What need” was there in that case that He should be called “after the order of Melchisedec and not after the order of Aaron”? Why did He set aside Aaron, and introduce a different priesthood, that of Melchisedec? “If then perfection,” that is the perfection of the things themselves, of the doctrines, of life, “had been by the Levitical priesthood.”
And observe how he goes forward on his path. He had said that [He was] “after the order of Melchisedec,” implying that the [priesthood] “after the order of Melchisedec” is superior: for [he was] far superior. Afterwards he shows this from the time also, in that He was after Aaron; evidently as being better.
2. And what is the meaning of what follows? “For” (he says) under [or “upon”] it the people have received the Law [or “have been legislated for”]. What is “under it” [&c.]? Orders itself by it; through it does all things. You cannot say that it was given to others, “the people under it have received the law,” that is, have used it, and did use it. You cannot say indeed that it was perfect, it did not govern the people; “they have been legislated for upon it,” that is, they used it.
What need was there then of another priesthood? “For the priesthood being changed, there is of necessity a change of the law also.” But if there must be another priest, or rather another priesthood, there must needs be also another law. This is for those who say, What need was there of a new Covenant? For he could indeed have alleged a testimony from prophecy also. “This is the covenant which I made with your fathers” [&c.]. But for the present he contends on the ground of the priesthood. And observe, how he says this from the first. He said, “According to the order of Melchisedec.” By this he excluded the order of Aaron. For he would not have said “After the order of Melchisedec,” if the other had been better. If therefore another priesthood has been brought in, there must be also [another] Covenant; for neither is it possible that there should be a priest, without a covenant and laws and ordinances, nor that having received a different priesthood He should use the former [covenant].
In the next place, as to the ground of objection: “How could He be a priest if He were not a Levite?” Having overthrown this by what had been said above, he does not even think it worth answering, but introduces it in passing. I said (he means) that the priesthood was changed, therefore also the Covenant is. And it was changed not only in its character, or in its ordinances, but also in its tribe. For of necessity [it must be changed] in its tribe also. How? For the priesthood being changed [or “transferred”], from tribe to tribe, from the sacerdotal to the regal [tribe], that the same might be both regal and sacerdotal.
And observe the mystery. First it was royal, and then it has become sacerdotal: so therefore also in regard to Christ: for King indeed He always was, but has become Priest from the time that He assumed the Flesh, that He offered the sacrifice. You see the change, and the very things which were ground of objection these he introduces, as though the natural order of things required them. “For” (he says) “He of whom these things are spoken pertained to another tribe.” I myself also say it, I know that this tribe [of Judah] had nothing of priesthood. For there is a transferring.
3. Yea and I am showing another difference also (he would say): not only from the tribe, nor yet only from the Person, nor from the character [of the Priesthood], nor from the covenant, but also from the type itself. Who was made [“became” so], not according to the law of a carnal commandment, but according to the power of an endless life. He became (he says) “a priest not according to the law of a carnal commandment”: for that law was in many respects unlawful.
What is, “of a carnal commandment”? Circumcise the flesh, it says; anoint the flesh; wash the flesh; purify the flesh; shave the flesh; bind upon the flesh; cherish the flesh; rest as to the flesh. And again its blessings, what are they? Long life for the flesh; milk and honey for the flesh; peace for the flesh; luxury for the flesh. From this law Aaron received the priesthood; Melchisedec however not so.
Source: Homilies on the Epistle to the Hebrews (New Advent)