Today Saturday 30th January, in Ordinary time, there is no obligatory memorial and so we can celebrate an optional memorial of the Blessed Virgin Mary, which I will do this lunchtime.
This liturgical attribution of Saturday to Mary was largely the work of Alcuin (735-804), the Benedictine monk who was “Minister of Education” at the court of Charlemagne and who contributed in a decisive manner to the Carolingian liturgical reform. Alcuin composed six formularies for Votive (that is, devotional) Masses – one for each day of the week. And he assigned two formularies to Saturday in honour of Our Lady. The practice was quickly and joyously embraced by both clergy and laity. The great theologians of the twelfth and thirteenth centuries, Sts. Bernard, Thomas, and Bonaventure explained the dedication of Saturdays to Mary by pointing to the time of Christ’s rest in the grave. Everyone else had abandoned Christ; only Mary continued to believe.
The Directory on Popular Piety and the Liturgy (2001), §188 says
“Whatever its historical origins may be, 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.”