a) On the weekdays of Advent from December 17 to December 24, on days within the Octave of the Nativity of the Lord, and on the weekdays of Lent, except Ash Wednesday and during Holy Week, the Mass texts for the current liturgical day are used; but the Collect may be taken from a Memorial which happens to be inscribed in the General Calendar for that day, except on Ash Wednesday and during Holy We