Trinity Sunday

Today is the Feast of the Most Holy Trinity. It is also the first Sunday after Pentecost, marking the return of 'green' time after the Septuagesima -Lent-Paschal period. The feast is now a Double of the First Class. The Office for a local feast seems to have originated in Liege in the tenth century and the celebration spread in northern France and England. The Franciscan John Peckham revised the texts in the thirteenth century. In 1334 the feast was extended to the Universal Calendar. It appears as a double of the Second Class in the Tridentine Missal of 1570 and was raised to Double of the First Class by Pius X.

The feast began with first Vespers on Saturday marking the beginning of the Summer (Aestiva) volume of the Breviarium Romanum. The Office is proper with proper antiphons and festal psalms although the chapter and hymn will be used at Vespers on Saturdays for all the Sundays after Pentecost. The antiphon on the Magnificat and the collect are proper. A commemoration is sung of the first Sunday after Pentecost. After Vespers the antiphon etc. Salve Regina returns.

At Mattins there are three nocturns. The antiphons and responsories are proper. In the first nocturn the lessons are from Isaiah. In the second nocturn they are taken from the Book of Bishop Fulgentius on faith and in the third nocturn from a homily of St. Gregory Nazianzen, the ninth lesson is of the first Sunday after Pentecost. At Lauds a commemoration of the Sunday is sung.

At Prime the Creed of St. Athanasius, Quicumque, is sung after the last unit of Ps. 118. Prior to Pius X Quicumque was sung on all Sundays throughout the year when the Office was Dominical. In many Uses, e.g. Sarum, it was sung on many more days in the year too.

Mass is sung after Terce. Before Mass at the sprinkling of lustral water the antiphon Asperges me returns. The Gloria is sung, the second collect is of the Sunday, the Credo is sung, the preface that of the Most Holy Trinity (used for all Sundays not having a proper preface after 1759), and the last Gospel of the Sunday.

In second Vespers a commemoration of the first Sunday after Pentecost is sung.

In the 'liturgical books of 1962' all commemorations of the first Sunday are omitted at both Vespers, Mattins and Lauds. Quicumque is only sung on this Sunday in the 1962 rite.