the 1960s Implementing the decision of the Council of Trent, Pope Pius V promulgated, in the Apostolic Constitution Quo primum of 14 July 1570, an edition of the Roman Missal that was to be in obligatory use throughout the Latin Church except where there was another liturgical rite that could be proven to have been in use for at least two centuries. Some corrections to Pope Pius V's text proved necessary, and Pope Clement VIII replaced it with a new typical edition of the Roman Missal on 7 July 1604. (In this context, the word "typical" means that the text is the one to which all other printings must conform.) A further revised typical edition was promulgated by Pope Urban VIII on 2 September 1634. Beginning in the late seventeenth century, France and neighbouring areas saw a flurry of independent missals published by bishops influenced by Jansenism and Gallicanism. This ended when Bishop Pierre-Louis Parisis of Langres and Abbot Guéranger initiated in the nineteenth century a campaign to return to the Roman Missal. Pope Leo XIII then took the opportunity to issue in 1884 a new typical edition that took account of all the changes introduced since the time of Pope Urban VIII. Pope Pius X also undertook a revision of the Roman Missal, which was published and declared typical by his successor Pope Benedict XV on 25 July 1920. Though Pope Pius X's revision made few corrections, omissions, and additions to the text of the prayers in the Roman Missal, there were major changes in the rubrics, changes which were not incorporated in the section entitled "Rubricae generales", but were instead printed as an additional section under the heading "Additiones et variationes in rubricis Missalis." In contrast, the revision by Pope Pius XII, though limited to the liturgy of only five days of the Church's year, was much bolder, requiring changes even to canon law, which until then had prescribed that, with the exception of Midnight Mass for Christmas, Mass should not begin more than one hour before dawn or later than one hour after midday. In the part of the Missal thus thoroughly revised, he anticipated some of the changes affecting all days of the year after the Second Vatican Council. These novelties included the first official introduction of the vernacular language into the liturgy for renewal of baptismal promises within the Easter Vigil celebration. Pope Pius XII