The Prophet is bid to set the two crowns on the head of the high priest. This, as I have said, was intended as a symbol to denote the union of the two dignities in the person of Christ. It was necessary until the coming of Christ to select the high priest from the posterity of Aaron; and it was also required that the kings should be from the seed of David; so that we observe a distinction between the royal office and the priesthood, not only as to the persons, but also as to the families. It would have indeed been a strange thing to see a king from the tribe of Levi; and it would have been contrary to God’s appointed order to see a priest from the tribe of Judah and from the family of David. Since then the king was adorned with his own diadem, and since the high priest had his own proper mitre, what could this mean, but that the same man was to wear two crowns? Doubtless we observe that there is here some change in the past order of things, and that there is something unusual set forth. But there is nothing new in this, — that the Redeemer, who had been promised, should be eminent as a king and a priest; for this had been predicted in the hundred and tenth Psalm, “Jehovah said to my Lord, sit on my right hand,” — this is what belongs to the right of a king; it afterwards follows, “Thou art a priest for ever, according to the order of Melchizedec.” Though kings must then have been chosen from the family of David and the tribe of Judah, and though priests must have then been taken from the Levitical tribe, yet the Spirit foretold, that a king would come who was to be a priest, as had been the case with Melchisedec. This very thing is what the Prophet now confirms.
Zechariah being ordered to set the crowns on the head of Joshua, we are not so to regard this, as though Joshua had immediately undertaken the two offices of a king and a priest; for he was satisfied with his own: but the Prophet shows in the type what was to be looked for at the coming of the Messiah; for the time had not yet come, when Christ should receive the royal diadem, as it is said in Ezekiel, —
“Take away the diadem; set it aside, set it aside, set it aside, until he shall come, whose it is.” (Ezekiel 21:26.)
We here see that the Prophet points out a length of time, during which the royal diadem was to be trodden as it were under foot. Though the royal crown had not yet laid in the dust sufficiently long, yet the Prophet did nothing presumptuously; for the Jews could not have conceived in their mind what is here promised, had not the typical priest come forth, wearing the two crowns. Nor could this have been so suitable to the person of Zerubbabel; for though he was of the family of David, and was a type of Christ, he had not yet the name of a king, nor had he any regal power: he could not therefore have been so suitable a person. It is then no wonder that God brought forth the high priest Joshua, who was a type and representative of Christ; and he brought him forth with a double crown, because he who was to come would unite, according to what follows, the priesthood with the kingly office.