Numbers 1071-1075 of the Catechism of the Catholic Church (CCC) treat sacred liturgy as source of life, as well as its relationship with prayer and catechesis. The liturgy is source of life first of all because it is the work of Christ (CCC, 1071). In the second place, because it is also an action of his Church (Ibid.). But, which is the reeminent of these two aspects? Moreover, what does the word life mean in this context?
Vatican Council II responds: From the liturgy, hence, and particularly from the Eucharist, grace flows in us as from a source, and obtained with the greatest efficacy is the sanctification of men in Christ and the glorification of God, to which all the other activities of the Church tend as to their end (Sacrosanctum Concilium [SC], 10). Understood thus is that, when the liturgy is called source of life, from it grace flows.
Already answered here is the first question: the liturgy is source of life primarily because it is the work of Christ, Author of grace.
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