An attempt to deal with the whole Liturgy of the Church within the compass of one small book of less than three hundred pages may seem a very bold venture. It would not, in fact, have been undertaken were if not that the publishers of the 'Civilta Cattolica' in Roma asked that such a book should be written for their series 'Manuali del pensiero cattolico' and specified the limits of its size. No doubt it will be easy enough to point out lacunae in this book, and to indicate subject which ought also to have been treated therein. But I am not without hope that the very limitation of its scope will render the book useful to a wider circle of readers, and that it may serve as an introduction which will lead them on to deeper study in the spirit of the liturgy.