« TU TRINITATIS UNITAS ». — Hymn of Friday Matins, by an unknown author of the fifth century. It is found in ninth-century manuscripts.
It is a profession of faith and a song of love to the Trinity of the divine Persons who, in mysterious unity, sustain and govern the world.
BIBL.: G. S. Piment, Les hymnes du Bréviaire romain, I, Paris 1874, p. 242–49; F. Vanderstuyf, Les hymnes de l'Ordinaire du Bréviaire, Paris 1912, p. 100; A. Mitra, Gli inni del Breviario romano, Naples 1947, p. 74. Silverio Mattei