PREFACE. - It is the solemn prayer of praise and thanksgiving sung or recited, after the Offertory has ended, at the beginning of the action of the Sacrifice. The word P. derives from the ancient use of a formula or prayer solemnly pronounced before an assembly (etymologically prae = in a local sense = coram). In the sense of a liturgical formula it occurs in can. 12 of the Second Council of Milevis (416) and in the Gregorian [Sacramentary]. In St. Cyprian (De oratione Dominica, 31) the word P. is found restricted to the introductory versicles "Sursum corda" ("praefatione praemissa... dicendo: Sursum corda"), this too in the ancient sense of an admonition or warning before the important action (prae in a temporal sense ante). In the times of St. Justin, of Hippolytus, of the Apostolic Constitutions down to the Middle Ages, the P. formed a single whole with the canon ("Incipit Canon actionis" of the Gelasian Sacramentary, as in the Gregorian one), at least the common P., while the others occur in the text. Under Gallican influence, the detached P. becomes a preliminary formula, but retains the first element of the ancient "Eucharistia" of praise and thanksgiving, while the other element, the supplication, becomes part of the Canon.
In the first centuries, the celebrant was left free to compose the P., but already the Traditio apostolica recommends using a formula. In the very ancient collection of Roman liturgical libelli (the so-called "Leonine" of Verona) there occur 267 P., in the "Gelasian" 54; in the 8th-century "Gelasian" of St. Gall 186. The traditional Roman use of the "Gregorian-Hadrian" has them only on the feasts of Christmas, Epiphany, Easter, Ascension, Pentecost and of the Apostles (Peter and Paul), as well as on particular occasions, now no longer in practice, such as in natali Papae, on the days in ordinatione presbyteri, for spouses, at a dedication of an altar. In the Middle Ages were added the P. of the Most Holy Trinity, of Lent, of the Passion and of the Madonna (under Urban V in 1095). This number of 11 P. is retained down to the present times, under the influence of the pseudo-decree attributed to Pelagius II (d. 500) by Burchard of Worms (d. 1025), later passed into the Decree of Gratian. Under Benedict XV in 1919 the P. of St. Joseph and of the dead are introduced; under Pius XI in 1925 that of Christ the King and in 1928 that of the Sacred Heart. Besides these P. of the universal Church, some dioceses (Lyons, Besançon) and some religious Orders have their own P.
The content of the P. comes from the great prayer of the "Eucharistia", of thanksgiving and praise, inaugurated by the bèrakhah of the Jews at the end of meals after the example of Christ at the Last Supper. In the sense of the most ancient tradition God is praised and thanks are given for the creation of the world, for all his benefits, especially for the Redemption, for the Passion and death of the Savior, for his Resurrection and Ascension. Thanks are given to the Father through his Son. This central theme of thanksgiving occurs already in the first documents, e.g., of the Didache, of St. Justin, of Hippolytus of Rome (Traditio apostolica), etc. The praise of God is very soon changed into thanksgiving.
The initial dialogue between the celebrant and the people contains the three traditional phrases with the corresponding responses of the people: the celebrant's greeting and the two exhortations Sursum corda (Jn 11:41; Col 3:1; Lam 3:41) and Gratias agamus (a similar formula pronounced by the Jews after the meal), already referred to by St. Cyprian and by Hippolytus. The fundamental scheme of the P. is contained in the common P.
It begins with the invocation to the Father (as also in the De sacramentis, IV, 5, 21, one reads better "Domine, sancte Pater, omnipotens aeterne Deus": cf. A. Baumstark, Liturgie comparée, 2nd ed., Chevetogne 1939, p. 72). Then comes an expansion according to the ecclesiastical year or the feast in three ways: a) after "Deus" one continues with "Et te... Iesum C. D. N. Per quem" (of the Madonna and of St. Joseph) or with "Qui... Per C. D. N. Per quem" (Lent and Passion); b) a Christological expansion is inserted "Quia... et ideo" (Christmas, Epiphany, Sacred Heart, Christ the King); at Easter the beginning is varied; c) the expansion follows after "Per C. D. N. Qui... Et ideo" (Ascension) or "Per C. D. N. In quo... Et ideo" (for the dead). Only the P. of the Apostles represents a supplication; all the others are hymns of glorification and thanksgiving. According to this content the style of the P. is also elevated and the melody varies in ferial and solemn tones. Other particulars: at the greeting, the celebrant does not turn toward the people, because the sacrifice has begun and he must no longer turn; during the singing, as throughout the Canon, the hands are held raised and extended. In the Eastern liturgy, unlike the Latin one, the P. is never changed, or is changed with the whole formula or liturgy.
In the Gallican liturgy the word P. is used as praefatio missae, in the sense of a preamble to the collect (as in the Latin-Roman liturgy on Good Friday). In the same sense the word P. occurs in praefatio symboli, praefatio orationis Dominicae in the Ordo of Baptism. The prayer corresponding to the Roman P. in the Gallican liturgy is called contestatio (a word perhaps already known to St. Augustine) or immolatio; in the Mozarabic liturgy inlatio.
After the example of the P. of the Mass, other P. were composed to be used outside the sacrifice on particular and solemn occasions: consecration of a bishop, ordination of a priest, of a deacon, of virgins, blessing of an abbot, blessing or consecration of things (church, palms, baptismal font, paschal candle, Exultet). To abbreviate the beginning of the P. "Vere... salutare", the sign formed by the initials of the first two words VD fused into a single monogram was used. Still simple in the Carolingian era, the monogram becomes very rich and developed in ample and sumptuous ornaments in the Romanesque era; simpler in the Gothic period in the 14th-15th centuries, it is omitted in printed books.