The first records of the texts of this great acclamation occur in apostolic times (Mt 21:9, c.f. Ps 118:26; Rev 5:8-9, c.f. Is 6:3; and Clement's first letter to the Corinthians 34:5-7). The use of the Sanctus in the Mass is first attested in the fourth century (Anaphora of Serapion, and Apostolic Constitutions). The use of the complete text in its current form is first attested in the sixth century in the Gallican Rite by Caesarius of Arles.
The oldest surviving Sanctus chant is that found in the Gregorian chant of the Ordinary of the Mass number XV, dated to the tenth century. It bears the marks of congregational singing, with repeated melodic phrases and no extended melismas.
Today, the Sanctus is the primary acclamation of the assembly in the Liturgy of the Eucharist. By its very nature It is a song, and should be sung by all while standing. It is a sign of the entire assembly joining itself with the heavenly liturgy in praise of God.
The Sanctus should begin immediately after the priest's invitation at the conclusion of the Preface. The entire assembly join with the priest in singing the Sanctus.What the General Instruction of the Roman Missal (GIRM) Says
The Different Elements of Mass
37. Finally, concerning the other formulas:
a. Some constitute an independent rite or act, such as the Gloria, the responsorial Psalm, the Alleluia and verse before the Gospel, the Sanctus, the Memorial Acclamation, and the song after communion;
b. Others accompany another rite, such as the chants at the Entrance, at the Offertory, at the
fraction (Agnus Dei), and at Communion.
Movements and Posture
43. The faithful should stand from the beginning of the Entrance chant, or while the priest approaches the altar, until the end of the Collect; for the Alleluia chant before the Gospel; while the Gospel itself is proclaimed; during the Profession of Faith and the Prayer of the Faithful; from the invitation, Orate, fratres (Pray, brethren); before the Prayer over the Offerings until the end of Mass, except at the places indicated below.
They should, however, sit while the readings before the Gospel and the responsorial Psalm are proclaimed and for the Homily and while the Preparation of the Gifts at the Offertory is taking place; and, as circumstances allow, they may sit while the period of sacred silence after Communion is observed.
But they should kneel at the consecration, except when prevented on occasion by reasons of health, lack of space, the large number of people present, or some other good reason. Those who do not kneel ought to make a profound bow when the priest genuflects after the consecration.
Nevertheless, it is up to the Conference of Bishops to adapt the gestures and postures described in the Order of Mass to the culture and reasonable traditions of the people. The Conference, however, must make sure that such adaptations correspond to the meaning and character of each part of the celebration. Where it is the practice for the people to remain kneeling after the Sanctus until the end of the Eucharistic Prayer and before Communion when the priest says: Ecce Agnus Dei (This is the Lamb of God), this practice is laudably retained.
With a view to a uniformity in gestures and postures during one and the same celebration, the faithful should follow the directions which the deacon, lay minister, or priest gives according to whatever is indicated in the Missal.
In Australia apart from what is said above, the people are to sit from the Preparation of the Gifts until the completion of the priest’s invitation Orate fratres, and then stand from the beginning of the people’s response: “May the Lord accept…” to the end of the Sanctus. They then kneel from the completion of the Sanctus until after the Great Amen, and then stand from the beginning of the invitation to the Lord’s Prayer until the completion of the Agnus Dei, when they are to kneel again until the distribution of Holy Communion. During the sacred silence after the distribution of Holy Communion, they may either sit or kneel.
The Individual Parts of the Mass
79. The chief elements making up the Eucharistic Prayer may be distinguished in this way:
a. Thanksgiving (expressed especially in the Preface): in which the priest, in the name of the entire holy people, glorifies God the Father and gives thanks for the whole work of salvation or for some special aspect of it that corresponds to the day, festivity, or season.
b. Acclamation: in which the whole congregation, joining with the heavenly powers, sings the Sanctus. This acclamation, which is part of the Eucharistic Prayer itself, is sung or said by all the people with the priest.
216. The Preface is sung or said by the principal priest celebrant alone; but the Sanctus is sung or recited by all the concelebrants, together with the congregation and the choir.
Singing and Music
31. To facilitate the children’s participation in singing the Gloria, Credo,Sanctus, and the Agnus Dei, it is permitted to use with the melodies appropriate vernacular texts, accepted by competent authority, even if these do not correspond exactly to the liturgical texts (cf. MS, 55).
Singing During Mass
27. For the celebration of the Eucharist with the people, especially on Sundays and feast days, a form of sung Mass (Missa in cantu) is to be preferred as much as possible, even several times on the same day.
28. The distinction between solemn, sung and read Mass, sanctioned by the Instruction of 1958 (n. 3), is retained, according to the traditional liturgical laws at present in force. However, for the sung Mass (Missa cantata), different degrees of participation are put forward here for reasons of pastoral usefulness, so that it may become easier to make the celebration of Mass more beautiful by singing, according to the capabilities of each congregation.
These degrees are so arranged that the first may be used even by itself, but the second and third, wholly or partially, may never be used without the first. In this way the faithful will be continually led towards an ever greater participation in the singing.
29. The following belong to the first degree:
(a) In the entrance rites: the greeting of the priest together with the reply of the people; the prayer.
(b) In the Liturgy of the Word: the acclamations at the Gospel.
(c) In the Eucharistic Liturgy: the prayer over the offerings; the preface with its dialogue and the Sanctus; the final doxology of the Canon, the Lord's prayer with its introduction and embolism; the Pax Domini; the prayer after the Communion; the formulas of dismissal.
30. The following belong to the second degree:
(a) the Kyrie, Gloria and Agnus Dei;
(b) the Creed;
(c) the prayer of the faithful.
31. The following belong to the third degree:
(a) the songs at the Entrance and Communion processions;
(b) the songs after the Lesson or Epistle;
(c) the Alleluia before the Gospel;
(d) the song at the Offertory;
(e) the readings of Sacred Scripture, unless it seems more suitable to proclaim them without singing.
32. The custom legitimately in use in certain places and widely confirmed by indults, of substituting other songs for the songs given in the Graduale for the Entrance, Offertory and Communion, can be retained according to the judgment of the competent territorial authority, as long as songs of this sort are in keeping with the parts of the Mass, with the feast or with the liturgical season. It is for the same territorial authority to approve the texts of these songs.
33. It is desirable that the assembly of the faithful should participate in the songs of the Proper as much as possible, especially through simple responses and other suitable settings.
The song after the lessons, be it in the form of gradual or responsorial psalm, has a special importance among the songs of the Proper. By its very nature, it forms part of the Liturgy, of the Word. It should be performed with all seated and listening to it—and, what is more, participating in it as far as possible.
34. The songs which are called the "Ordinary of the Mass," if they are sung by musical settings written for several voices may be performed by the choir according to the customary norms, either a capella, or with instrumental accompaniment, as long as the people are not completely excluded from taking part in the singing.
In other cases, the parts of the Ordinary of the Mass can be divided between the choir and the people or even between two sections of the people themselves: one can alternate by verses, or one can follow other suitable divisions which divide the text into larger sections. In these cases, the following points are to be noted: it is preferable that the Creed, since it is a formula of profession of faith, should be sung by all, or in such a way as to permit a fitting participation by the faithful; it is preferable that the Sanctus, as the concluding acclamation of the Preface, should normally be sung by the whole congregation together with the priest; the Agnus Dei may be repeated as often as necessary, especially in concelebrations, where it accompanies the Fraction; it is desirable that the people should participate in this song, as least by the final invocation.
35. The Lord's Prayer is best performed by the people together with the priest.
If it is sung in Latin, the melodies already legitimately existing should be used; if, however, it is sung in the vernacular, the settings are to be approved by the competent territorial authority.
36. There is no reason why some of the Proper or Ordinary should not be sung in said Masses. Moreover, some other song can also, on occasions, be sung at the beginning, at the Offertory, at the Communion and at the end of Mass. It is not sufficient, however, that these songs be merely "Eucharistic"—they must be in keeping with the parts of the Mass, with the feast, or with the liturgical season.