Our series in the book of Hebrews has us in Chapter 7, where the writer explains how the mysterious character of Melchizedek is a type of Christ. Although Mel is only mentioned a few times in the Old Testament, he becomes instrumental with the writer of Hebrews who reveals how Jesus established a permanent priesthood, according to the order of Melchizedek.
The law which came through Moses had to come to an end — every jot and title — otherwise Jesus could not have been considered an authentic High Priest forever in this New Covenant. A complete change of law was needed.