The Eucharistic celebration is 'the center of the Christian community,' 'the source and summit of the Christian life,' or further, 'the center and culmination of the entire life of the Christian community.' Root, source, center, summit: the Eucharistic celebration is at the heart of our faith and our life. To study it is to look at its own heart. That is where we meet Jesus Christ, present in his Word, present in the Eucharist, present in the celebrating community." From these words of introduction to his concluding remarks, Father Deiss offers an explanation of the post-Vatican II Mass that is as remarkable for its simplicity as it is for its thoroughness. He examines the structure of the celebration as revealed by Vatican II, a structure that, in his words, appears now "simpler, more luminous, more beautiful" than ever before. Lucien Deiss, C.S.Sp., for ten years a professor of theology and Scripture at the Grand Scholasticat de Chevilly-Larue, is one of the pioneers of the biblical and liturgical renewal. He worked for the reform brought about by Vatican II and participated in the ecumenical translation of the Bible. He is the author of numerous books, including Celebration of the Word; Springtime of the Liturgy; The Mass; and Joseph, Mary, Jesus, published by The Liturgical Press. He has composed many liturgical songs, some of which have been translated into the principal world languages, including Chinese.