I. Blessed be God; let us proceed, brethren, from wonders to the miracles of the Lord, and as it were, from strength to strength. For just as in a golden chain the links are so intimately joined and connected together, as that the one holds the other, and is fitted on to it, and so carries on the chain— even so the miracles that have been handed down by the holy Gospels, one after the other, lead on the Church of God, which delights in festivity, and refresh it, not with the meat that perishes, but with that which endures unto everlasting life. Come then, beloved, and let us, too, with prepared hearts, and with ears intent, listen to what the Lord our God shall say unto us out of the prophets and Gospels concerning this most sacred feast. Verily, He will speak peace unto His people, and to His saints, and to those which turn their hearts unto Him. Today, the trumpet-blast of the prophets have roused the world, and have made glad and filled with joyfulness the churches of God that are everywhere among the nations. And, summoning the faithful from the exercise of holy fasting, and from the palaestra, wherein they struggle against the lusts of the flesh, they have taught them to sing a new hymn of conquest and a new song of peace to Christ who gives the victory. Come then, every one, and let us rejoice in the Lord; O come, all you people, and let us clap our hands, and make a joyful noise to God our Saviour, with the voice of melody. Let no one be without portion in this grace; let no one come short of this calling; for the seed of the disobedient is appointed to destruction.— Let no one neglect to meet the King, lest he be shut out from the Bridegroom's chamber.— Let no one among us be found to receive Him with a sad countenance, lest he be condemned with those wicked citizens— the citizens, I mean, who refused to receive the Lord as King over them. Let us all come together cheerfully; let us all receive Him gladly, and hold our feast with all honesty. Instead of our garments, let us strew our hearts before Him, In psalms and hymns, let us raise to Him our shouts of thanksgiving; and, without ceasing, let us exclaim, “Blessed is He that comes in the name of the Lord;” for blessed are they that bless Him, and cursed are they that curse Him. Again I will say it, nor will I cease exhorting you to good, Come, beloved, let us bless Him who is blessed, that we may be ourselves blessed of Him. Every age and condition does this discourse summon to praise the Lord; kings of the earth, and all people; princes, and all judges of the earth; both young men and maidens — and what is new in this miracle, the tender and innocent age of babes and sucklings has obtained the first place in raising to God with thankful confession the hymn which was of God taught them in the strains in which Moses sang before to the people when they came forth out of Egypt— namely, “Blessed is He that comes in the name of the Lord.”
II. Today, holy David rejoices with great joy, being by babes despoiled of his lyre, with whom also, in spirit, leading the dance, and rejoicing together, as of old, before the ark of God, he mingles musical harmony, and sweetly lisps out in stammering voice, Blessed is He that comes in the name of the Lord. Of whom shall we inquire? Tell us, O prophet, who is this that comes in the name of the Lord? He will say it is not my part today to teach you, for He has consecrated the school to infants, who has out of the mouth of babes and sucklings perfected praise to destroy the enemy and the avenger, in order that by the miracle of these the hearts of the fathers might be turned to the children, and the disobedient unto the wisdom of the just. Tell us, then, O children, whence is this, your beautiful and graceful contest of song? Who taught it you? Who instructed you? Who brought you together? What were your tablets? Who were your teachers? Do but you, they say, join us as our companions in this song and festivity, and you will learn the things which were by Moses and the prophet earnestly longed for. Since then the children have invited us, and have given unto us the right hand of fellowship, let us come, beloved, and ourselves emulate that holy chorus, and with the apostles, let us make way for Him who ascends over the heaven of heavens towards the East, and who, of His good pleasure, is upon the earth mounted upon an ass's colt. Let us, with the children, raise the branches aloft, and with the olive branches make glad applaud, that upon us also the Holy Spirit may breathe, and that in due order we may raise the God-taught strain: “Blessed is He that comes in the name of the Lord; Hosanna in the highest.” Today, also, the patriarch Jacob keeps feast in spirit, seeing his prophecy brought to a fulfilment, and with the faithful adores the Father, seeing Him who bound his foal to the vine mounted upon an ass's colt. Today the foal is made ready, the irrational exemplar of the Gentiles, who before were irrational, to signify the subjection of the people of the Gentiles; and the babes declare their former state of childhood, in respect of the knowledge of God, and their after perfecting, by the worship of God and the exercise of the true religion. Today, according to the prophet, is the King of Glory glorified upon earth, and makes us, the inhabitants of earth, partakers of the heavenly feast, that He may show himself to be the Lord of both, even as He is hymned with the common praises of both. Therefore it was that the heavenly hosts sang, announcing salvation upon earth, “Holy, holy, holy, is the Lord God of hosts; the whole earth is full of His glory.” And those below, joining in harmony with the joyous hymns of heaven, cried: “Hosanna in the highest; Hosanna to the Son of David.” In heaven the doxology was raised, “Blessed be the glory of the Lord from His place;” and on earth was this caught tip in the words, “Blessed is he. that comes in the name of the Lord.”
Source: Oration on the Psalms (New Advent)