The Roman Catholic Church’s current theology of liturgy is influenced in a marked degree by the fruits of an intellectual movement whose roots lie mainly in the nineteenth century but which came to fruition in the twentieth. This movement is generally referred to as The Liturgical Movement. Pope Pius XII gave official ecclesiastical approval to this Movement of theologians, by commending it in his encyclical letter Mediator Dei (1947). The Catholic Church’s authoritative recent statement on liturgy, Sacrosanctum Concilium (Constitution on the Sacred Liturgy, 1963) of the Second Vatican Council (1962–65), remains deeply imbued with the principles of the Liturgical Movement. The Movement took its rise in the 1830s from the work of Abbot Gueranger of the Benedictine monastery of Solesmes in France. Its ideas were developed more widely in academic and pastoral life during the twentieth century but especially in the Benedictine monasteries of Beuron and Maria-Laach (Germany), and Maredsous and Mont-Cesar (Belgium). These Benedictine environments, with their emphasis on the liturgy celebrated frequently throughout the day, were particularly fertile places for exploring and developing new approaches to liturgical activity and liturgical theology.