In the Constitution on the Sacred Liturgy, the Second Vatican Council wrote that liturgical reform and renewal must accord with what they called "the spirit of the liturgy." But what did they mean by this "spirit"? In the decades prior to the Council, the Popes spoke of this same spirit. But the most solid source of this term rests upon a book published in 1918, The Spirit of the Liturgy by Roman Guardini. In his remarkable book, which Pope Benedict XVI claims began the liturgical movement in Germany, Guardini lays out seven core principles of the liturgical spirit, principles that the Second Vatican Council saw as integral to authentic liturgical reform. In this work, eight experts on the liturgy recall Guardini's spiritual insights, explaining how these can deepen our liturgical understanding and practice today. The contributors are Bishop Arthur Serratelli, Fr. Cassian Folsom, O.S.B., Dr. Michon Matthiesen, David Fagerberg, Fr. Daniel Card , Bishop James Conley, Fr. Emery de Ga l, and Susan Benofy.