On Saturdays in Ordinary Time when there is no obligatory memorial, an optional memorial of the Blessed Virgin Mary is allowed.
Saturdays stand out among those days dedicated to the Virgin Mary. These are designated as memorials of the Blessed Virgin Mary. This memorial derives from Carolingian times (ninth century), but the reasons for having chosen Saturday for its observance are unknown. While many explanation have been advanced to explain this choice, none is completely satisfactory from the point of view of the history of popular piety.
Prescinding from its historical origins, today the memorial rightly emphasizes certain values “to which contemporary spirituality is more sensitive: it is a remembrance of the maternal example and discipleship of the Blessed Virgin Mary who, strengthened by faith and hope, on that great Saturday on which Our Lord lay in the tomb, was the only one of the disciples to hold vigil in expectation of the Lord's resurrection; it is a prelude and introduction to the celebration of Sunday, the weekly memorial of the Resurrection of Christ; it is a sign that the “Virgin Mary is continuously present and operative in the life of the Church”.
Popular piety is also sensitive to the Saturday memorial of the Blessed Virgin Mary. The statutes of many religious communities and associations of the faithful prescribe that special devotion be paid to the Holy Mother of God on Saturdays, sometimes through specified pious exercises composed precisely for Saturdays.