Feast of the Circumcision of Christ of Jesus. Pope John XXIII's 1960 rubrical and calendrical revision called 1 January simply the Octave of the Nativity. (This 1960 calendar was incorporated into the 1962 Roman Missal, whose continued use is authorized by the motu proprio "Summorum Pontificum".) The 1969 revision states: "1 January, the Octave Day of the Nativity of the Lord, is the Solemnity of Mary, the Holy Mother of God, and also the commemoration of the conferral of the Most Holy Name of Jesus." The Anglican communion's "Book of Common Prayer" liturgy celebrates this day as the Circumcision of Christ. Since 2000, the "Common Worship"
Revised Julian calendar grace, presumably including its acceptance of the new calendar. The basic justification for the new calendar is the known errors of the Julian calendar, which will in the course of time lead to a situation in which those following the Julian calendar will be reckoning the month of December (and the feast of Christ's Nativity) during the heat of summer, August and its feasts during the deep cold of winter, Easter during the autumn season, and the November feasts in the springtime. This would conflict with the Church's historic practice of celebrating Christ's birth on , a date chosen for