as an answer of the server to the
Epistle or
Prophecies; in
High Mass this answer should not be sung by the choir. In the
Mozarabic and
Gallican Rite the Deo gratias follows the title of the Epistle or the Prophecy; at its end the Amen is said. The Orthodox churches do not use this formula in connection with the Epistle. In the Latin Church the Deo gratias is not said on
Ember Saturday after the fifth
lesson, which is followed by the canticle of the Three Young Men in the furnace, in order not to interrupt the sense; neither is it said after the lessons on
Good Friday or after the Prophecies on
Holy Saturday and the eve of
Pentecost;
after the second
Gospel, while after the first Gospel the server answers Laus tibi Christe (praise be to you, Christ). Quarti[1] explained this by saying that the first Gospel signifies the preaching of Christ, while the second Gospels signifies the preaching of the Apostles, while Holweck (1908) holds such an interpretation to be "artificial and arbitrary";
in the
Breviary the Deo gratias is used more frequently; in
Matins (except the last three days of Holy Week and the office of the Dead) after every lesson answering to the invocation: Tu autem
Domine miserere nobis; also after the
capitula, the short lesson in
Prime and
Compline; and in answer to the Benedicamus Domino Compline; and in answer to the Benedicamus Domino at the close of every Hour. The Mozarabic Breviary puts the Deo gratias after the title of the lesson, the Amen to the end.
The formula Deo gratias was used in extra-liturgical prayers and customs by the Christians of all ages. The
rule of St. Benedict prescribes that the doorkeeper shall say Deo gratias, as often as a stranger knocks at the door or a beggar asks for assistance.
When
St. Augustine announced to the people the election of his coadjutor and successor, Evodius of
Uzalis, they called out Deo gratias thirty-six times.[2]
In
Africa it was the salutation used by the Catholics to distinguish themselves from the
Donatists who said Deo laudes instead.[3]
Therefore, in Africa, Deo gratias was used as a Catholic given name, e.g.
St. Deogratias, Bishop of Carthage (r. 453–456).
The name of the deacon for whom St. Augustine wrote his treatise De catechizandis rudibus was also called Deogratias.
Felix of Cantalice (1515–1587) used this interjection so often that the people called him "Brother Deogratias".
Musical settings
Deo gratias has been set to music by several composers.