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

Like the byzantine churches which, on the 4th Sunday of lent, celebrate a feast to honour the holly Wood of the Cross, the Roman liturgy dedicates this Sunday, called jadis in vigesima, to the celebration of the glories of the triumphant banner of redemption.

The Introït is taken from Isaias (66 : 10-11), where the Prophet, foreseeing the future destinies of the Church, exhorts Jerusalem to rejoice, and invites those who were in mourning because of her to now rejoice with her, because the Lord wants to inundate her with consolation. Psalm 121 follows, chosen because of the frequent mention made therein of Jerusalem. This day is properly the feast of Holy Jerusalem.

The Gradual comes from Psalm 121 and praises Jerusalem. The mere announcement of the return from the exile in Babylon to the holy City fills the faithful soul with joy, as it feels itself delivered of the weight of the body and free to take flight towards heaven.

The psalm of the Tract is the 124th, nearly identical in inspiration to the 121st.

Today, out of respect for the Sunday solemnity, the fast is suspended - but not the abstinence from flesh meat, which, for the ancients, continued rigorously throughout Lent, as even now among the Russians and Orientals - the Church almost invites us to enjoy a little respite in order to pursue with more energy the cycle of penance. To this end, the liturgy evokes for us the memory of Jesus who, in the desert, multiplied the bread and fishes (Jn. 6:1-15) in order to feed the five thousand.

The antiphon of the Offertory is taken from Psalm 134: "Praise ye the Lord, for He is good: sing ye to His name, for He is sweet: whatsoever He pleased, He hath done in heaven and in earth."

The versicle for the psalm (121) of the Communion resumes singing the glories of the mystical City of God, the heavenly Jerusalem.