« GLORIA PATRI ». — A formula of praise and glorification of all three Divine Persons, it is a simple development of the Trinitarian baptismal formula (Mt. 28:19). Its author and the time of its introduction into the liturgy cannot be determined.
The doxology was used by the Fathers in various forms: that of « G. P. per Filium in Sp. S. », almost universally in the East (Origen, De orat., 33), or that of « G. P. cum Filio et Sp. S. » (Martyrium Polycarpi, 14, 3, 22, 3). Finally, as the watchword of the orthodox, the formula was changed to « G. P. et Filio et Sp. S. » (a Syrian inscription of 569; Flavian of Antioch at the Council of 381), whereas the Arians retained the first « G. P. per F. in Sp. S. », which was not erroneous in itself but was wrongly interpreted by them (St. Basil, De Spiritu Sancto, of 375). In the Mozarabic liturgy, in accordance with Ps. 28:2, one says « Gloria et honor Patri et F. et Sp. S. », according to the Fourth Council of Toledo, canon XV, of 633, whose author was St. Isidore.
The doxology was supplemented by the final clause « in saecula saeculorum. Amen », very common among the Jews (v. ROMA. 16, 27; Hebr. 13, 21); it is still used today, alone, in the Mozarabic liturgy; the Greeks and Latins preface it with « Et nunc et semper et ». Peculiar to the Western Churches alone (excluding Spain), the clause begins with « Sicut erat in principio », introduced in the fifth century, also as a protest against the Arians, according to its first attestation at the Council of Vaison (529); it is doubtful what its subject is, whether the term « Gloria », the Son, or an implicit subject.
The doxology « G. P. » is used as a psalm verse at the end of the psalms in the Office, except during the sacred triduum; in the Mass only with the Judica psalm (42) of the Introit and with that of the Lavabo (25), here too except during Passiontide and in Requiem Masses. The addition gives every psalm a Christian character; it was perhaps first used in Antioch in antiphonal singing and spread throughout the world with it; in the time of St. Benedict its use was general. In extraliturgical use, the « G. P. » was always one of the most popular formulas; the first part is regarded as a profession of faith, sometimes accompanied by the Sign of the Cross.