Summary of comments of this office by Dom Schuster, in his work L'année liturgique.

BLESSING OF THE PALMS AND PROCESSION

During the Middle Ages it was the rule that the great ceremonies of the paschal week, as the ancients called these days that are about to begin, took place near the pontifical residence in the Lateran palace.

When the pope arrived at the porch, he would sit upon the throne while the doors of the church remained shut, and the lead cantor and the prior of the basilica, at the head of all the clergy participating in the ceremony, would intone the hymn Gloria, Laus, prescribed in the missal even today.

The passage from St. Matthew read this day recounting the solemn entry of Jesus into the holy City (21:1-9) was already designated by the liturgy of Jerusalem in the second half of the fourth century.

During the distribution of blessed palms or olive branches, the choir executes the following antiphons taken from the Gospel just read: "The Hebrew children bearing branches of olive, went forth to meet the Lord, crying out, and saying: ‘Hosanna in the highest!'"

Today it is the children who have the place of honor in the feast, because God is pleased by simple and innocent souls, and it is to them that He reveals His secrets. "The Hebrew children spread their garments in the way, and cried out, saying, ‘Hosanna to the Son of David; blessed is He that cometh in the name of the Lord.' "

Then the procession takes place; and while today it has a special meaning, recalling the triumphant entry of Jesus into Jerusalem, it is nonetheless also a vestige of the ancient Sunday procession which, in the Middle Ages, regularly preceded the Mass, especially in the Benedictine abbeys.

During the procession, the choir executes the following antiphons: "The multitude goeth out to meet the Redeemer with flowers and palms, and payeth the homage due to a triumphant conqueror: nations proclaim the Son of God; and their voices rend the skies in the praise of Christ: ‘Hosanna!'"

Antiphon: "Let us join in faith with the angels and children, singing to the conqueror of death: ‘Hosanna in the highest! ' "

Antiphon: "A great multitude that was met together at the festival cried out to the Lord: ‘Blessed is He that cometh in the name of the Lord! Hosanna in the highest!' "

Antiphon: "Six days before the paschal solemnity, when the Lord arrived at the city of Jerusalem, the children went forth to meet him, carrying in their hands palm branches, and they cried out "Hosanna, blessed are you who come in your infinite mercy. ‘Hosanna in the highest.' "

After the antiphons comes the hymn Gloria, Laus, etc. with the ceremony where the crossbearer knocks at the doors of the temple to make them open to the cortege.

THE MASS

The Mass begins immediately after the procession, but it has a character completely different from the benediction of the palms; it is in more intimate relation with the liturgy of the preceding days.

The Introït is taken from the Psalm 21 that Jesus Christ intoned on the Cross, and which so admirably depicts His sufferings: "O Lord, keep not Thy help far from me: look to my defense: deliver me from the lion's mouth, and my lowness from the horns of the unicorns."

The Gradual1 is borrowed from Psalm 72, and is a prelude to the triumph of next Sunday: "I was moved at the sight of the wicked, indignant at the mortal torpor in which the sinners, beaten, lay. But Thou, however, Father, hast held me by my right hand; and by Thy will Thou hast conducted me, and with Thy glory Thou hast received me."

The Tract, or psalm in directum, is the 21st, in which are described first the excruciating agony of Jesus, and of his sentiments of humility, interior desolation, and confident trust in God; then it praises the triumph of the messianic redemption, and announces the new generation, that is, the Church, to which the message of the Gospel will be addressed.

The reading of the Gospel according to St. Matthew contains the whole narrative of the Lord's Passion (Ch. 26-27), from the Last Supper with the apostles to the sealing of the tomb. The choice of this Gospel reading is very ancient for Rome, because it is attested by the Ordines of the ninth century.

The antiphon of the Offertory is taken from Psalm 68, which also preludes the Lord's Passion: "My heart hath expected reproach and misery; and I looked for one that would grieve together with Me, but there was none: I sought for one that would comfort Me, and I found none; and they gave Me gall for My food, and in My thirst they gave Me vinegar to drink."

The antiphon for the Communion was taken from St. Matthew (26:42): "Father, if this chalice may not pass away, but I must drink it, Thy will be done."