The Constitution on the Sacred Liturgy of the Second Vatican Council teaches us:
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. (n.8)
A Sacrament is an efficacious sign of grace, instituted by Christ and entrusted to the Church, by which divine life is given to us. Full and active participation in the sacramental life of the Church requires a period of preparation of both mind and heart to be receptive to the grace of new life in Christ.