The authorship of this psalm--which is said daily in Matins--is attributed to David in the Septuagint and Vulgate. Its Latin form in the invitatory differs slightly from the Vulgate text. The Breviary retains here the text of St. Jerome's revision and the Vulgate contains the second and more correct revision. _Hymns_. The hymn is an answer to the invitation given to us in the invitatory, to praise God and to rejoice with Him. It is a song of joy and praise. Hymns were introduced into the Divine Office in the Eastern Church before the time of St. Ambrose (340-397). To combat the Arians, who spread their errors by verse set to popular airs, St. Ambrose, it is said, introduced public liturgical hymn-singing in his church in Milan, and his example was followed gradually through the Western Church. (See Note A, _infra_.) The final stanza of a Breviary hymn is called the doxology ([Greek: doxa] praise, [Greek: logos] speech), a speaking of praise. Hymns which have the final stanza proper, the _Ave Maris stella_, Lauds hymn of the Blessed Sacrament, Matins hymn for several Martyrs, the first Vesper hymn of the Office of Holy Cross, and the Vesper hymns of St. Venantius and St. John Cantius, never change the wording of the stanza. But, _where the metre of the hymn_ admits such a change as possible in the last stanza. (a) From Christmas to Epiphany _Jesu tibi sit gloria, Qui natus es de Virgine_ is inserted in all hymns, even on saints' offices. (b) From Epiphany till end of its octave, _Jesu tibi sit gloria, Qui apparuisti gentibus_. (c) From Low Sunday till Ascension Thursday, on Pentecost Sunday and its octave, all hymns end in _Deo Patri sit gloria, Et Filio qui a mortuis_. This is the ending for all hymns of saints' feasts in Paschal times, excepting those hymns mentioned above. (d) From Ascension to Pentecost (except in the hymn _Salutis humanae Sator_) the doxology is _Jesu tibi sit gloria, Qui victor in coelum redis_. (e) Feast of Transfiguration has _Jesu, tibi sit gloria, Qui te revelas parvulis_. In all other hymns the doxology is read as it is printed in the Breviary. _Antiphons_. Antiphon, coming from Greek words meaning a re-echoing of the sound, is a chant performed alternately by two choirs, and was used in pagan drama, long before the Christian era. At what date it was introduced into Church liturgy it is difficult to determine. Some say it was introduced by St. Ignatius, second Bishop of Antioch. It is certain that it was used by bishops and priests to attract, retain and teach the faithful during the Arian heresy. In church music, the lector ceased to recite the psalm as a solo and the faithful divided into two choirs, united in the refrain _Gloria Patri_.