Q: You posted before that you do not believe the Triduum is one continuous liturgy. The USCCB, however, says the Triduum is a “single celebration” (https://www.usccb.org/prayer-worship/liturgical-year/triduum). Just as the Mass is composed of 2 liturgies (Word and Eucharist), why can’t the Triduum be considered one continuous liturgy composed of other liturgies like the Mass?
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A: The page you reference comes from the Prayer and Worship section of the USCCB website, not from the USCCB’s Office of Divine Worship. You generally find inspirational more than legislative material on this section of the site. You notice that the declaration of this being “liturgically one day” carries no footnote. There is no official source that one could cite to make that case.
The Triduum certainly has a magnificent unity to it. No single service contains the entire paschal mystery, and all three of them express it eloquently as a whole. As I indicated here https://paulturner.org/triduum-3/, one thing that helps me think of the three days is the role of the Liturgy of the Hours, which still includes introductions, blessings and dismissals—that is, a beginning and an end of independent liturgies.
To your specific question, could it be considered one liturgy composed of several, as any typical Mass is, then you have to account for the two Masses that the Triduum already embraces, the Lord’s Supper and the Vigil, and I just find it a stretch to say that somehow that’s all the same liturgy.
But unquestionably, once you start with the Mass of the Lord’s Supper, you are on a liturgical journey that does not end until Easter Sunday, and the meaning of any single element requires participation in the rest.