The modern liturgical movement owes a great debt to Solesmes monk Dom Eughne Cardine (1905-1988), whose tireless research in the ancient manuscripts uncovered the elusice secrets of Gregorian Rhythm, thus revealing some of the original pristine beauty of Gregorian chant. In this volume, Dom Cardine sums up the origin, decline and restoration of the chant, and challenges researchers to continue his work.