Special Masses and Devotions
7. … 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).
13. Popular devotions of the Christian people are to be highly commended, provided they accord with the laws and norms of the Church, above all when they are ordered by the Apostolic See…
… these devotions should be so drawn up that they harmonize with the liturgical seasons, accord with the sacred liturgy, are in some fashion derived from it, and lead the people to it, since, in fact, the liturgy by its very nature far surpasses any of them.
from Articles 7 and 13 in the CONSTITUTION ON THE SACRED LITURGY, SOLEMNLY PROMULGATED BY HIS HOLINESS POPE PAUL VI ON DECEMBER 4, 1963