The first volume of a three-part Liturgicae Institutiones set, De Sacra Liturgia Universim is a comprehensive study on liturgical matters for both the clergy and laity.
Published in its final edition posthumously after Callewaert's death on the Feast of the Transfiguration of Our Lord in 1943, this liturgical work is perhaps his crowning glory.
The American Ecclesiastical Review (Volume 62) had this to say about De Sacra Liturgia Universim in its book review of 1920:
The present volume is the introductory one to a series comprising the liturgical interpretation of the Breviary, Missal, Ritual, and the ecclesiastical cycle under the title Annus ecclesiasticus.
The author treats his subject of the Liturgy in general not merely as a Prolegomena* but as a distinct branch of the Institutiones Liturgicae [foundations of the liturgy]. Accordingly he distinguishes cult or worship from the liturgical expression of the same, as set forth in the history of the Church. The first part enters upon the analysis of the subject in its broad aspects, considering the end and purpose of the liturgical service, the principal and secondary ministry, the fruits, from the doctrinal, moral, and ascetical points of view. The historical aspect begins with the apostolic tradition and follows up the successive practice and legislation through the periods of Oriental, Gallican, Roman, and various local usages, down to the reforms of Trent and the evolution of the seventeenth to the twentieth century.
*NB: a formal essay used to introduce and outline an extended work.
The latter half of the volume is devoted to an inquiry into the sources of liturgical legislation, the early collections and the interpreting bodies such as the Sacred Congregations. A special article is devoted to the study of the texts, the preferences and corrections represented by the literary monuments and typical editions of the Roman liturgy. The final chapter, "De Liturgica Scientia ejusque Methodo", is intended to guide the student in the systematic inquiry as to the manner of exposition. There is a chapter on customs, also a good analytical index. The author has in press a practical guide on the Mass, under the title Caeremoniale in celebrandis Missis tam privatis quam solemnibus, in Vesperis et Laudibus SS. Sacramenti servandum.
