Before we dismiss the subject, it may be well to remind the reader that this mention of a Surety by our author is the _locus classicus_ of the Federalist school of divines. Cocceius and his followers present the whole range of theological doctrines under the form of covenant. They explain the words “Surety of a better covenant” to mean that Christ is appointed by God to be a Surety on behalf of men, not on behalf of God. The course of thought in the passage is, we think, decisive against this interpretation. At the same time, we readily admit that their doctrine is a just theological inference from the passage. If God swears that His gracious purposes will be fulfilled and ordains Jesus to be His Surety to men, and if also the fulfilment of the Divine promise depends on the fulfilment of certain conditions on the part of men, the oath of God will involve His enabling men to fulfil those conditions, and the Surety will become in eventual fact a Surety on behalf of men. But this is only an inference. It is not the meaning of the Apostle’s words, who only speaks of the Surety on the part of God. The validity of the inference now mentioned depends on other considerations extraneous to this passage. With those considerations, therefore, we have at present nothing to do. _Fourth_, the climax of the argument is reached when the Apostle infers the endless duration of Christ’s one priesthood.[133] The number of men who had been successively high-priests of the old covenant increased from age to age. Dying one after another, they were prevented from continuing as high-priests. But Melchizedek had no successor; and the Jews themselves admitted that the Christ would abide for ever. The ascending argument of the Apostle proves that He ever liveth, and has, therefore, an immutable priesthood. For, first, He is of the royal tribe, and the oath of God to David guarantees that of his kingdom there shall be no end. Again, in the greatness of His personality, He is endowed with the power of an endless life. Moreover, as Priest He has been established in His office by oath. He is, therefore, Priest for ever.