Principles of the Liturgy is the first book of the newly revised and newly translated work THE CHURCH AT PRAYER, under the general editorship of A. G. Martimort, honorary dean of the faculty of theology, Toulouse.

Principles of the Liturgy outlines the complex history and development of liturgical practices. From its foreshadowings in the Old Testament to the reformed rites of the Vatican II, we are made aware, along the way, of liturgy's role in the Church and, as A. G. Martimort says, as an "expression of life." The authors introduce us to the contributions made to the Church's "sacred actions" from art and music, from theological reflection on historical data, and from our present-day human sciences of anthropology, sociology, psychology, and linguistics.

The other volumes in the work are: II The Eucharist (1986); III The Sacraments (Fall 1987); and IV The Liturgy and Time (1986).