The term liturgy, now classic and consecrated by the profession, that is, however, relatively recent use in the West._x000D_
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Since the beginning of the liturgical movement (1909) until Vatican II, most authors strove to give a definition of the liturgy to summarize briefly its nature and its essential characteristics. However, none of the proposed definitions seemed satisfactory. In its constitution Sacrosanctum Concilium, promulgated on December 4, 1963, the Second Vatican Council opened its exhibition of the "general principles for reform and progress of the liturgy," thus establishing a definition of it._x000D_
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The work that the reader is holding emphasizes the spiritual and pastoral guidance of the reform to be bound to the name of Pope Paul VI and develop knowledge of the various forms that the Church has given his sentence under the circumstances from geographical and historical origins of Christianity.