This lecture was given at the Catholic University of America on May 16, 2023 as part of the Thomistic Institute symposium titled "Toward a Fundamental Theology of the Priesthood." For more information on upcoming events, please visit our website at www.thomisticinstitute.org. About the speaker: Fr. Mark Morozowich pursued a vocation to the priesthood in the Ukrainian Catholic Eparchy of St. Josaphat in Parma, Ohio. He served in Pittsburgh and in Butler, Pennsylvania before beginning doctoral studies at the Pontifical Oriental Institute in Rome that yielded a comprehensive study of Holy Thursday Liturgy in Jerusalem and Constantinople from the Fourth to the Fourteenth Centuries. He lectures as an Associate Professor of Liturgy at The Catholic University of America, served as the Associate Dean for Seminary and Ministerial Programs, and is dean of The School of Theology and Religious Studies. His research focuses upon various topics of liturgical history from penitential practices and the liturgical year to divergent issues in Eastern Christian Mysteries.