In the earthly liturgy we take part in a foretaste of that heavenly liturgy which is celebrated in the holy city of Jerusalem toward which we journey as pilgrims, where Christ is sitting at the right hand of God, a minister of the holies and of the true tabernacle; we sing a hymn to the Lord's glory with all the warriors of the heavenly army; venerating the memory of the saints, we hope for some part and fellowship with them; we eagerly await the Saviour, Our Lord Jesus Christ, until He, our life, shall appear and we too will appear with Him in glory.
The sacred liturgy does not exhaust the entire activity of the Church. Before men can come to the liturgy they must be called to faith and to conversion: "How then are they to call upon him in whom they have not yet believed? But how are they to believe him whom they have not heard? And how are they to hear if no one preaches? And how are men to preach unless they be sent?" (Rom. 10:14-15).
Therefore the Church announces the good tidings of salvation to those who do not believe, so that all men may know the true God and Jesus Christ whom He has sent, and may be converted from their ways, doing penance. To believers also the Church must ever preach faith and penance, she must prepare them for the sacraments, teach them to observe all that Christ has commanded, and invite them to all the works of charity, piety, and the apostolate. For all these works make it clear that Christ's faithful, though not of this world, are to be the light of the world and to glorify the Father before men.
Nevertheless the liturgy is the summit toward which the activity of the Church is directed; at the same time it is the font from which all her power flows. For the aim and object of apostolic works is that all who are made sons 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.
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. 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.
Devotions proper to individual Churches also have a special dignity if they are undertaken by mandate of the bishops according to customs or books lawfully approved.