4 These, then, were the words of praise addressed to Jesus by the multitude, “Hosanna: blessed is He that comes in the name of the Lord, the King of Israel.” What a cross of mental suffering must the Jewish rulers have endured when they heard so great a multitude proclaiming Christ as their King! But what honor was it to the Lord to be King of Israel? What great thing was it to the King of eternity to become the King of men? For Christ's kingship over Israel was not for the purpose of exacting tribute, of putting swords into His soldiers' hands, of subduing His enemies by open warfare; but He was King of Israel in exercising kingly authority over their inward natures, in consulting for their eternal interests, in bringing into His heavenly kingdom those whose faith, and hope, and love were centred in Himself. Accordingly, for the Son of God, the Father's equal, the Word by whom all things were made, in His good pleasure to be King of Israel, was an act of condescension and not of promotion; a token of compassion, and not any increase of power. For He who was called on earth the King of the Jews, is in the heavens the Lord of angels.
5. “And Jesus, when He had found a young ass, sat thereon.” Here the account is briefly given: for how it all happened may be found at full length in the other evangelists. But there is appended to the circumstance itself a testimony from the prophets, to make it evident that He in whom was fulfilled all they read in Scripture, was entirely misunderstood by the evil-minded rulers of the Jews. Jesus, then, “found a young ass, and sat thereon; as it is written, Fear not, daughter of Zion: behold, your King comes, sitting on an ass's colt.” Among that people, then, was the daughter of Zion to be found; for Zion is the same as Jerusalem. Among that very people, I say, reprobate and blind as they were, was the daughter of Zion, to whom it was said, “Fear not, daughter of Zion: behold, your King comes, sitting on an ass's colt.” This daughter of Zion, who was thus divinely addressed, was among those sheep that were hearing the Shepherd's voice, and in that multitude which was celebrating the Lord's coming with such religious zeal, and accompanying Him in such warlike array. To her was it said, “Fear not:” acknowledge Him whom you are now extolling, and give not way to fear when He comes to suffering; for by the shedding of His blood is your guilt to be blotted out, and your life restored. But by the ass's colt, on which no man had ever sat (for so it is found recorded in the other evangelists), we are to understand the Gentile nations which had not received the law of the Lord; by the ass, on the other hand (for both animals were brought to the Lord), that people of His which came of the nation of Israel, and was already so far subdued as to recognize its Master's crib.
6. “These things understood not His disciples at the first; but when Jesus was glorified,” that is, when He had manifested the power of His resurrection, “then remembered they that these things were written of Him, and they had done these things unto Him,” that is, they did nothing else but what had been written concerning Him. In short, mentally comparing with the contents of Scripture what was accomplished both prior to and in the course of our Lord's passion, they found this also therein, that it was in accordance with the utterance of the prophets that He sat on an ass's colt.
7. “The people, therefore, that was with Him when He called Lazarus out of his tomb, and raised him from the dead, bare record. For this cause the crowd also met Him, for that they heard that He had done this miracle. The Pharisees, therefore, said among themselves: Perceive ye that we prevail nothing? Behold, the whole world is gone after Him.” Mob set mob in motion. “But why are you, blinded mob that you are, filled with envy because the world has gone after its Maker?”
8. “And there were certain Gentiles among them that had come up to worship at the feast: the same came therefore to Philip, who was of Bethsaida of Galilee, and desired him, saying, Sir, we would see Jesus. Philip comes and tells Andrew: and again Andrew and Philip tell Jesus.” Let us hearken to the Lord's reply. See how the Jews wish to kill Him, the Gentiles to see Him; and yet those, too, were of the Jews who cried, “Blessed is He that comes in the name of the Lord, the King of Israel.” Here, then, were they of the circumcision and they of the uncircumcision, like two house walls running from different directions and meeting together with the kiss of peace, in the one faith of Christ. Let us listen, then, to the voice of the Cornerstone: “And Jesus answered them, saying, The hour has come that the Son of man should be glorified.” Perhaps some one supposes here that He spoke of Himself as glorified, because the Gentiles wished to see Him. Such is not the case. But He saw the Gentiles themselves in all nations coming to the faith after His own passion and resurrection, because, as the apostle says, “Blindness in part has happened to Israel, until the fullness of the Gentiles should be come in.” Taking occasion, therefore, from those Gentiles who desired to see Him, He announces the future fullness of the Gentile nations, and promises the near approach of the hour when He should be glorified Himself, and when, on its consummation in heaven, the Gentile nations should be brought to the faith. To this it is that the prediction pointed, “Be Thou exalted, O God, above the heavens, and Your glory above all the earth.” Such is the fullness of the Gentiles, of which the apostle says, “Blindness in part is happened to Israel, till the fullness of the Gentiles come in.”
Source: Tractates on the Gospel of John (New Advent)