Blessed Trinity Sunday, everyone! I was reading my Marian Missal today, and it provided some beautiful insights into the nature of this feast and the season that follows.
"Glory be to the Father, and to the Son, and to the Holy Ghost. As it was in the beginning, is now, and ever shall be, world without end. Amen.
As soon as we have celebrated the Advent of the Holy Ghost, we celebrate in song the feast of the Holy Trinity in the office of the following Sunday.
The place is well chosen, for, immediately after the descent of this Divine Spirit, began the preaching and belief, and, through Baptism, faith, and confession in the Name of the Father, the Son, and the Holy Ghost. (St. Rupert.)"
Season after Pentecost:
"This season begins with the Feast of the Blessed Trinity and is the longest of the Liturgical Year. It may comprise from 24-28 weeks and differs considerably from the other liturigical seasons.
In a Liturgical Year there is a historical progression, beginning in Advent with the waiting for the coming of the Messias, followed by His birth at Christmas. During the Sundays after Epiphany, the Holy Childhood is commemorated, while during Lent we are reminded of the fasting in the desert and the Passion of Our Lord. The sacred cycle is completed in the eastertide, when we celebrate the Ressurection and Ascenscion of Our Lord and the Descent of the Holy Ghost upon the Apostles.
In this last part of the ecclesiastical year, the Church, led by the Holy Ghost, continues the work of the Redemption, realized during the preceding part of the Liturugical Year.
'The Holy Ghost, Whom the Father will send in My Name, He will teach you all things, and bring all things to your mind whatsoever I shall have said to you.'
This last season of the Liturgical Year is filled with feasts of major importance: those of the Blessed Trinity, Corpus Christi, the Sacred Heart, The Assumption and Nativity of Our Lady, All Saints, and All Souls."
This feast provides the last link in the cycle of our salvation, and at the same time encompasses it in its entirity, uniting the end: Pentecost, which marked when man was brought into union with the Trinity through baptism, with the beginning: The Annunciation, the Holy Spirit's descent upon the daughter of God the Father to make her the mother of God the Son.
Blessed be the holy Trinity and undivided Unity: we will give glory to Him, because He hath shown His mercy to us. (Introit, Trinity Sunday)