Constitution on the Liturgy
The
 1963 Constitution on the Liturgy was the first document of the Second 
Vatican Council.  In this constitution, new principles were 
proclaimed as Church teaching, to help us to pray in the spirit of the 
liturgy.
God . . . when the 
fullness of time had come sent his Son, the Word made flesh, anointed by
 the Holy Spirit, to preach the Gospel to the poor, to heal the contrite
 of heart, to be a "bodily and spiritual medicine," the Mediator between
 God and man. For his humanity, united with the person of the Word, was 
the instrument of our salvation. (5)
Just
 as Christ was sent by the Father, so also he sent the apostles, filled 
with the Holy Spirit . . . From that time onwards the Church has never 
failed to come together to celebrate the paschal mystery: reading those 
things "which were in the scriptures concerning him" (Luke 24:27), 
celebrating the Eucharist in which "the victory and triumph of death are
 again made present," and at the same time giving thanks "to God for his
 unspeakable gift" (2 Cor. 9:15) in Christ Jesus, "in praise of his 
glory" (Eph. l:12), through the power of the Holy Spirit. (6) . . .
To
 accomplish so great a work, Christ is always present in his Church, 
especially in her liturgical celebrations.  He is present in the 
sacrifice of the Mass, not only in the person of his minister, "the same
 now offering, through the ministry of priests, who formerly offered 
himself on the cross," but especially under the Eucharistic 
species.  By his power he is present in the sacraments, so that 
when a man baptizes it is really Christ himself who baptizes. He is 
present in his word, since it is he himself who speaks when the holy 
scriptures are read in the Church.  He is present, lastly, when the
 Church prays and sings, for he promised: "Where two or three are 
gathered together in my name, there am I in the midst of them" (Matt. 
18:20).
Christ indeed always 
associates the Church with himself in this great work wherein God is 
perfectly glorified and men are sanctifed. The Church is his beloved 
Bride who calls to her Lord and through him offers worship to the 
Eternal Father. . .
Rightly, 
then, the liturgy is considered as an exercise of the priestly office of
 Jesus Christ. In the liturgy the sanctification of man is signified by 
signs perceptible to the senses and is effected in a way which 
corresponds to each of these signs. In the liturgy the whole public 
worship is performed by the mystical body of Jesus Christ, that is, by 
the head and his members.
From
 this it follows that every liturgical celebration, because it is an 
action of Christ the priest and of his body which is the Church, is a 
sacred action surpassing all others.  No other action of the Church
 can equal its efficacy by the same title and to the same degree. .
 . (7)
The liturgy is the
 summit towards which the activity of the Church is directed. At the 
same time, it is the fount from which all her power flows. For the aim 
and object of apostolic works is that all who are made sons and 
daughters of God, by faith and baptism, should come together to praise 
God in the midst of his Church, to take part in the sacrifice, and to 
eat the Lord's Supper. . . (10)
But
 in order that the liturgy may be able to produce its full effects, it 
is necessary that the faithful come to it with proper dispositions, that
 their minds should be attuned to their voices, and that they should 
cooperate with divine grace lest they receive it in vain. . .(11)
Pastors
 of souls must therefore realize that, when the liturgy is celebrated, 
something more is required than the mere observation of the laws 
governing valid and licit celebration. It is their duty also to ensure 
that the faithful take part fully aware of what they are doing, actively
 engaged in the rite, and enriched by its effects. (11)
Mother
 Church earnestly desires that all the faithful should be led to that 
full, conscious, and active participation in liturgical celebrations 
which is demanded by the very nature of the liturgy. Such participation 
by the Christian people is their right and duty by reason of their 
baptism. They are "a chosen race, a royal priesthood, a holy nation, 
a people redeemed." (1 Peter 2:9; cf. 2:4-5).
IN
 THE RESTORATION AND PROMOTION OF THE SACRED LITURGY, THIS FULL AND 
ACTIVE PARTICIPATION BY ALL THE PEOPLE IS THE AIM TO BE CONSIDERED 
BEFORE ALL ELSE.  It is the primary and indispensable source from 
which the faithful are to derive the true Christian spirit.  
Therefore, pastors of souls must zealously strive to achieve it, by 
means of the necessary instruction, in all their pastoral work.
Yet
 it would be futile to entertain any hopes of realizing this unless the 
pastors themselves, in the first place, become thoroughly imbued with 
the spirit and power of the liturgy, unless they undertake to give 
instruction about it. A prime need, therefore, is that attention be 
directed, first of all, to the liturgical instruction of the clergy. 
(14)
. . . With zeal and 
patience, pastors of souls must promote the liturgical instruction of 
the faithful, and also their active participation in the liturgy, both 
internally and externally, taking into account their age and condition, 
their way of life, and standard of religious culture. By so doing, 
pastors will be fulfilling one of the chief duties of a faithful 
dispenser of the mysteries of God. In this matter, they must lead their 
flock not only in word but also by example. (15)
.
 . . Liturgical services are not private functions but are celebrations 
of the Church, which is the "sacrament of unity," namely, the holy 
people united and ordered under their bishops.
Therefore,
 liturgical services pertain to the whole body of the Church; they 
manifest it and have effects upon it. They concern, however, the 
individual members of the Church in different ways, according to their 
differing rank, function, and actual participation. (26)
It
 is to be stressed that whenever rites, according to their specific 
nature, make provision for communal celebration involving the presence 
and active participation of the faithful, this way of celebrating them 
is to be preferred, so far as possible, to a celebration that is 
individual and quasi-private. 
This
 applies with special force to the celebration of Mass and the 
administration of the sacraments, even though every Mass has of itself a
 public and social nature. (27)
In 
liturgical celebrations, each person, minister or lay person who has a 
function to carry out should do all (but only) those parts which pertain
 to his function, by the nature of the rite and the principles of 
liturgy. (28)
Servers, 
lectors, commentators, and members of the choir also exercise a genuine 
liturgical function.  Therefore, they ought to discharge their task
 with the sincere piety and decorum  demanded by so exalted a 
ministry and rightly expected of them by God's people.
Consequently,
 they must all be deeply imbued with the spirit of the liturgy, each in 
his own measure. They must be trained to carry out their functions in a 
correct and orderly manner.  (29)
To
 promote active participation, the people should be encouraged to take 
part by means of acclamations, responses, psalmody, antiphons, and 
songs, as well as by actions, gestures, and bodily attitudes.  At 
the proper times, all should observe a reverent silence. (30)