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| From “Missale Sacri Ordinis Praedicatorum"; 1933 | 
The ferial days in Advent have the rank of III Class, until December 17.  During these days, when a III Class feast occurs in the Proper of the Saints, a commemoration is made of the ferial day at Lauds and Vespers.  From December 17 through December 23, the ferial days have the rank of II Class.  During this period, when a III Class feast occurs, the ferial office is prayed and a commemoration of the III Class feast is made at Lauds and Vespers.  The preces are prayed on all of these ferial days.

