See Lumen gentium, n°. 50. Quote: "Fully conscious of this communion of the whole Mystical Body of Jesus Christ, the pilgrim Church from the very first ages of the Christian religion has cultivated with great piety the memory of the dead, and "because it is a holy and wholesome thought to pray for the dead that they may be loosed from their sins", also offers suffrages for them. The Church has always believed that the apostles and Christ's martyrs who had given the supreme witness of faith and charity by the shedding of their blood, are closely joined with us in Christ, and she has always venerated them with special devotion, together with the Blessed Virgin Mary and the holy angels. The Church has piously implored the aid of their intercession. To these were soon added also those who had more closely imitated Christ's virginity and poverty,×and finally others whom the outstanding practice of the Christian virtues and the divine charisms recommended to the pious devotion and imitation of the faithful."
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One or more of the preceding sentences incorporates text from a publication now in the public domain: Herbermann, Charles, ed. (1913). "Votive Mass". Catholic Encyclopedia. New York: Robert Appleton Company.