Almighty and everlasting God, who hast given unto thy servants, in the confession of a true Faith, to acknowledge the glory of the eternal Trinity, and in the might of majesty to adore the Unity; we beseech thee that we may be defended by the constancy of that same Faith from all adversaries. Through...
Omnipotens sempiterne Deus, qui dedisti famulis tuis in confessione verae Fidei, aeternae Trinitatis gloriam agnoscere, et in potentia maiestatis adorate Unitatem; quaesumus, et ejusdem Fidei firmitate ab omnibus muniamur adversi per.
Introit: Blessed be the Holy Trinity and the undivided Unity
Ps: O Lord, our Lord: how excellent is thy name.
Epistle: Roman 11: 33-36. O the depth of riches...
Gradual: Blessed art thou O Lord who beholdest the deep
Gospel: John 3: 1-15. There was a man of the Pharisees...
This day marks the Feast of the Holy Trinity. There is a defining mark of catholicism in the worship of the Trinity in Unity. Its location on our calendar is significant as it directly follows the most important events that we celebrate: Resurrection, Ascension, and Whitsun-day
It differs from the historical events on the calendar as it is in recognition of a universal doctrine.
Thomas Becket was consecrated Archbishop of Canterbury on this Sunday, and his first official act was to set it aside for a new festival of the Holy Trinity. This feast was not accepted into the western church fully until 1332. This day was, and is in fact, the Octave of Pentecost. Originally it had propers related to Pentecost. The Gospel we have set before us today is a vestige of the Pentecost Octave.
There was a Trinity type of office used on Sundays in the early church to counter the Arian controversy with canticles, responses, a preface, and hymns. One Trinity hymn which continues this day as a creed is the Quicunque vult from the 5th century (likely by Hilary)
Now on to the collect:
"Almighty and everlasting God, who hast given unto thy servants in the confession of a true Faith to acknowledge the glory of the eternal Trinity, and in the might of majesty to adore the Unity; "
The "true faith" is that which we have confessed from the earliest days of the Church and which is in scripture, the baptismal covenant, and the creeds.
" we beseech thee that we may be defended by the constancy of that same Faith from all adversaries. "
Next follows the petition--we ask that by constant fidelity to the true Faith confessed above, that we may be defended from all adversity
The Gospel bears witness to Trinity in the words of the Lord to Nicodemus. It is only through the Holy Spirit that a man may be regenerated and reconciled to the Father through the Son. Our Lord said, "We speak that which we know": is not that collective "We" indeed the Father, Son, and Holy Ghost?http://god.com/books/god1/sect12.php
An homily of Hilary on the Trinity
(Portions were paraphrased and passages cited from The Collect of the Day, by Paul Zeller Strodach, 1939, The United Lutheran Press, Philadelphia) http://www.cyberhymnal.org/bio/s/t/r/strodach_pz.htm
The Ancient Collect: Its history and form