Blind horses of Zechariah 12:4
John Calvin made many references to the Church in his commentary on Zechariah 12, but he applied the prophecy to the Jews. 
Commenting on whether the prophecy of Zechariah 12 applies to the Christian Church, Ernst Wilhelm Hengstenberg wrote in his Christology of the Old Testament: 
The Christian Church is from its very commencement the legitimate continuation of Israel, the wicked having been rooted out from the nation, and those who were Gentiles by birth having been incorporated into Israel on the ground of their faith. The Saviour himself clearly indicated this at the very outset, by calling his Church “Israel” (Matt. xix. 28); and it was from this point of view alone, that the number of apostles appointed for the whole Church (Matt. xxviii. 19), corresponded to that of the tribes of Israel. According to Paul there is but one olive tree, one people of God, one Israel from the beginning to the end. In Rom. xi. 18, Israel is represented as the root of the Christian Church. In Rom. xi. 7,—”the election hath obtained it, the rest are hardened,”—the emphasis must not be laid upon the latter in a one-sided manner. According to Eph. ii. 12 and 19, when the Gentiles come to Christ, they are incorporated into the “commonwealth of Israel,” as “fellow-citizens with the saints” (“Israelis;” Bengel). That Israel is the root of the Christian Church is also apparent from the intercessory prayer of Christ (John xvii. 6—8), where he refers to the Church on earth as founded already, before a single Gentile had been admitted into it.
Charles H. H. Wright (1836-1909) alluded to Hengstenberg’s work in his comments on the same prophecy. Wright also tentatively suggested that the prophecy applied to the Christian Church. He wrote: 
The older Christian expositors, as Jerome and Cyrill, and many Reformation divines, as Luther, Tremellius, Piscator, Marck, etc., have explained Israel in this and the following chapters to signify directly the Christian Church. Others, as L. Cappellus and Calmet, view the name Israel as used in a double sense; firstly, to indicate the literal Israel in post-exilian days, especially in the Maccabean times, and secondly, the Christian Church, of which Israel was the type.
The prophecy, on the other hand, has been regarded as a continuation of those preceding it. According to this view, Zechariah takes up the thread of prophecy which he had dropped at the close of the last chapter, and speaks of the things which were to follow in chronological order. The events recorded in this chapter, according to this view, are those which happened immediately after the rejection of Christ by the Jewish people. In such a case a sort of typical interpretation must be adopted, and the Christian Church considered as the legitimate continuation of Israel, as Hengstenberg expresses it. It will not be forgotten that our Lord chose twelve apostles, corresponding to the twelve tribes of Israel, and promised them, as the reward of fidelity, that they should judge the twelve tribes of Israel (Matt. xix. 28); a promise which is evidently not susceptible of a literal interpretation, but which is true in relation to the Church of Christ (comp. Rev. xxi. 12, vii, 4-8), which, as composed of Israelites and Gentiles, is represented as one olive tree (Rom. xi. 16-21), one flock (John x. 16), one people, one nation (1 Pet. ii, 9, 10), being the very commonwealth of Israel (Eph. ii. 12, 18-22), the Israel of God (Gal. vi. 16).
To this interpretation it has been objected, that an Old Testament prophet could not possibly have understood Israel to have meant the Church, as Luther, Tremellius, Chr. B. Michaelis, have supposed. This objection is met by Hengstenberg’s view, that the Church is “the legitimate continuation of Israel.” The prophet may not, indeed, have thus understood his own words. While he imagined that he was speaking about his own people, he may have been led by the Spirit to speak about the Israel of God.
Matthew Henry stated in his commentary on Zechariah 12: 
The apostle (Gal. 4:25, 26) distinguishes between “Jerusalem which now is, and is in bondage with her children”—the remaining carcase of the Jewish church that rejected Christ, and “Jerusalem that is from above, that is free, and is the mother of us all”—the Christian church, the spiritual Jerusalem, which God has chosen to put his name there; in the foregoing chapter we read the doom of the former, and left that carcase to be a prey to the eagles that should be gathered to it. Now, in this chapter, we have the blessings of the latter, many precious promises made to the gospel-Jerusalem by him who (v. 1) declares his power to make them good. It is promised, I. That the attempts of the church’s enemies against her shall be to their own ruin, and they shall find that it is at their peril if they do her any hurt (v. 2-4, 6). II. That the endeavours of the church’s friends and patrons for her good shall be pious, regular, and successful (v. 5). III. That God will protect and strengthen the meanest and weakest that belong to his church, and work salvation for them (v. 7, 8). IV. That as a preparative for all this mercy, and a pledge of it, he will pour upon them a spirit of prayer and repentance, the effect of which shall be universal and very particular (v. 9-14). These promises were of use then to the pious Jews that lived in the troublous times under Antiochus, and other persecutors and oppressors; and they are still to be improved in every age for the directing of our prayers and the encouraging of our hopes with reference to the gospel-church.
Carl Friedrich Keil, a former student of Hengstenberg, refrained from applying the prophecy of Zechariah 12 to the Christian Church, and applied it to Jews instead. On Zechariah 12:4, Keil wrote: 
Ver. 4. “In that day, is the saying of Jehovah, will I smite every horse with shyness, and its rider with madness, and over the house of Judah will I open my eyes, and every horse of the nations will I smite with blindness.” These verses allude to an attack on the part of the nations upon Jerusalem and Judah, which will result in injury and destruction to those who attack it.
In Psalm 32:9, people who lack understanding are likened to horses: “Be ye not as the horse, or as the mule, which have no understanding: whose mouth must be held in with bit and bridle, lest they come near unto thee.”
Using the interpretation of horses suggested by Psalm 32:9, it seems the Bible scholars and commentators who fail to see that Jerusalem, the house of David, and the Jews in prophecies such as Zechariah 12 are symbolic of the Christian Church fulfill Zachariah’s prophecy; they are figuratively blind horses.
1. John Calvin. Commentary on Zechariah.
2. Ernst Wilhelm Hengstenberg. Christology of the Old Testament, and a commentary on the Messianic predictions, Volume 4. T. & T. Clark, 1858. pp. 58-60.
3. Charles Henry H. Wright. Zechariah and his prophecies, considered in relatin to modern criticism; with a comm. and new transl. (Bampton Lectures). 1879. pp. 357-358.
4. Matthew Henry’s Whole Bible Commentary Zech. 12:1
5. Carl Friedrich Keil, Franz Delitzsch. The twelve minor prophets, Volume 2. T. & T. Clark, 1868, pp. 379ff.
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