Fr. Mark Morozowich is the Dean of the School of Theology and Religious Studies at the Catholic University of America, an ecclesiastical faculty with special authority from the Vatican to teach theology.
Morozowich explained to CNA the principles that govern "enculturation," or deference to local circumstances, within the Mass.
"The Church has always enculturated the liturgy," he said. "This is something we've done through the centuries in every single place from the very beginning."
Starting with the first ministry of the apostles, he said, "the Church lived Jesus Christ, proclaimed his cross, death, and resurrection. The Church proclaimed Jesus Christ being present body and soul in the elements of the Eucharist."
He said that there have been, and continue to be, some regional differences in the matter used in the celebration of the Eucharist, but those differences are limited by the Church's doctrinal teaching.
"Classically, we can look at the very clear acceptance of the Byzantine rite having a leavened bread for its Eucharist, whereas the Roman Church has an unleavened bread for its Eucharist."
"Both are different but yet both are valid matter according to their own ritual tradition," Morozowich said. "This is something that has been going on for two thousand years."
"Some people talk about the use of something else besides wheat flour or the use of something besides wine in the Eucharist; one important part of this is certainly about [remembering] what we are expressing in this prayer, but there's a continuity to the sacrifice of Christ when he was on this Earth. That basic principle needs to be reflected in all these discussions."
The Mass is not, Morozowich said, about enacting an exact historical recreation of the last supper, "but at the same time the Church has said there are some core elements of this reality of the presence of this way the [Christian] community has celebrated throughout its life time."
"The Church needs to be very cautious with what are the latest 'fads' if you will," he said. "The Church is very concerned to present the culture and the prayers in a way that is telling and faithful to the way they have been lived through the centuries."
Even within the differences between the Latin and Byzantine rites, he said, there is an essential continuity of Eucharistic matter.
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"Leavened or unleavened, the Church has always used wheat bread. Whether it is mixed with hot or cold water, or mixed once or twice, the Church has always used wine," Morozowich said.
"These are essential, so that as the believer celebrates the Eucharistic and reflects on the institution of that Eucharist, they have a sense of a transcending of time and a sense of the true presence that is mediated through these specific elements."