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

Originally, at Rome, the feast of Pentecost terminated the fifty-day cycle of Eastertide, and inaugurated the fasting of the summer Ember days. Then the solemnity began to be prolonged for the following two days, and finally, after St. Leo the Great, it took in the whole week, equal to the octave of Easter.

The Introït, later on made famous by St. Thomas thanks to the office he composed for the feast of Corpus Christi, is taken from Psalm 80. It alludes to the neophytes who, yesterday, have drunk the delectable mix of milk and honey which they were given to taste after their baptism and first Holy Communion. "He fed them with the finest of wheat, and filled them with honey out of the rock."

In the versicle of the Alleluia, taken from the Acts, it is said that the Apostles published the wonders of the Lord in divers languages.

The antiphon of the Offertory is the same as that of Easter Tuesday. God, in His indignation against cruel Satan, who held the human race captive, has let out a great cry, a cry which caused the earth to tremble, the mountains to cover themselves, and to let flow the hidden springs concealed in their depths.

The antiphon of the Communion is taken from the Gospel according to St. John (14:26). It contains the promise of the Holy Ghost with the assurance of His special assistance such that the Church will never lose anything of the divine deposit confided to her.