The manner celebrating Mass, administering the sacraments and sacramentals, reciting the Divine Office, and performing other ecclesiastical functions, as authorized for the city and diocese of Rome. Its origin goes back to the more or less common but variable rite of the first three centuries. From the time of Pope St. Gregory the Great (reigned 590-604) the history was uniform, with four major stages of development. In the twelfth century the Roman Rite came to be used wherever Latin was used. During the Middle Ages it branched out into a great number of other rites, differeing however only in unimportant details. In the sixteenth century (1570) Pope St. Pius V abolished most of these derived rites, but the Roman Rite by then had been deeply influenced by and received additions from the Gallican and Spanish rites. In the twentieth century, as a result of the Second Vatican Council, major revisions were again made. Yet, as Pope Paul VI declared, these revisions are not to contradict the Roman Rite, since "what is Roman is the foundation of our Catholicity" (Allocution Facile Conicere, October 14, 1968).