We need to be very familiar with the world of liturgy, because for us to be truly human and Christian we need to have our life to be liturgical. We have to enter into this world presented to us by our faith, and much richer than what our senses and intelligence alone can perceive and understand.
It's in the liturgy where we unite ourselves fully with Christ our Savior and receive the merits of his redemptive work. It's in the liturgy where the living Christ offers himself to the Father together with us.
We are not left with a symbol only of Christ in the liturgy. That's because the sacramental signs used in the liturgy, especially the Eucharistic species, are no ordinary signs that simply point to another reality. In the sacraments, the signs themselves, the matter and form that comprise them, are Christ himself and his grace.
In the liturgy, man is united with God, time with eternity, earth with heaven. It is the best union we can have with God on earth. In a sense, with it we enter into the most perfect dimension of our life, into the fullest scope of reality. Obviously, we need to be aware of this nature of the liturgy, so we would know how to act and live in it.
The fullness of the liturgy takes place in the Holy Eucharist which is described as the "source and summit of the Christian life." The Catechism explains it this way:
"The other sacraments, and indeed all ecclesiastical ministries and works of the apostolate, are bound up with the Eucharist and are oriented toward it. For in the Blessed Eucharist is contained the whole spiritual good of the Church, Christ himself, our Pasch." (1324)
The whole Christ, the Son of God, who became man, born of the Virgin Mary, who taught and made miracles, who suffered, died and was buried, and resurrected on the third day, and ascended into heaven, etc., is there in the liturgy, especially in the sacrament of Holy Eucharist.
He did not become man, shared our human nature and condition except sin, and redeemed us with his death and resurrection, only to have all these events swallowed up in the past. His redemptive work has eternal value, is always in the present.
Whenever we are celebrating the Eucharist, receiving communion or visiting the Blessed Sacrament, we are truly and directly dealing with Christ!
In a sense, with the liturgy we become contemporaries with Christ, and together with him as in one whole body, the Mystical Body of Christ, we are the ones who celebrate the liturgy.
It's important to realize though that "the members do not all have the same function." The clergy, who by their sacred ordination become the very icon of Christ, preside at the Mass while the rest unite themselves with him, such that the whole assembly becomes what is termed as "leitourgos," ministers in their respective ways.
This is an important point to realize. The lay faithful who attend the Mass are no mere spectators or some pious extras. They celebrate by offering to God the Father, together with Christ's offering of his own self, whatever praises, thanksgiving, petitions and expiations they have.
In the Mass, what prayer and sacrifice we make get united with the most acceptable and pleasing prayer and sacrifice of Christ to his Father. It's the most amazing union we can have with Christ.
No greater windfall, bonanza or jackpot can we have than to have Christ offering his life on the cross for our salvation. Our sin has caused God to be with us. It's that "happy fault" referred to in the Easter vigil hymn, Exsultet. "O happy fault that earned for us so great, so glorious a Redeemer!"
Still, in the Mass we have to respect the different functions proper to each member of the assembly. The Catechism says:
"In the celebration of the sacraments it is thus the whole assembly that is 'leitourgos,' each according to his function, but in the 'unity of the Spirit' who acts in all. 'In liturgical celebrations each person, minister or layman, who has an office to perform, should carry out all and only those parts which pertain to his office by the nature of the rite and the norms of the liturgy.'" (1144)
The effectivity of the Mass derives from the power of Christ's work rather than the role we play in it (ex opera operato Christi). Just the same, it would be most ideal if we put ourselves in the best condition and dispositions when celebrating the Mass.