Charles H. Spurgeon on Psalms 110:4

Melchizedek. Some heretics of old affirmed that he was the Holy Ghost. Others, that he was an angel. Others, that he was Shem, the son of Noah. Others, that he was a Canaanite, extraordinarily raised up by God to be a priest of the Gentiles. Others, that he was Christ himself, manifested by a special dispensation and privilege unto Abraham in the flesh, who is said to have seen his day, and rejoiced, Joh 8:56. Difference there is also about Salem, the place of which he was king. Some take it for Jerusalem, as Josephus and most of the ancients. Others for a city in the half tribe of Manasseh, within the river Jordan, where Hierom reports that some ruins of the palace of Melchizedek were in his days conceived to remain. Tedious I might be in insisting on this point who Melchizedek was. But when I find the Holy Ghost purposely concealing his name, genealogy, beginning, ending, and descent, and that to special purpose, I cannot but wonder that men should toil themselves in the dark to find out that of which they have not the least ground of solid conjecture, and the inevidence whereof is expressly recorded, to make Melchizedek thereby the fitter type of Christ's everlasting priesthood. Edward Reynolds.