today's readings are 2 Maccabees 6: 18-31; Psalm 3 and Lk. 19: 1-10
Today's feast is one that we do not find in the Gospel accounts but is found in an ancient Christian document known as the Protoevangelium of James. In this account the author, connects the story of Mary's birth and childhood with many of the stories of holy women and men found in the Old Testament.
Today's feast became part of the Church's calendar in 1585, and celebrates Mary, in her later role as Theotokos, i.e., the Mother of God.
A wonderful article about this can be found in today's Faith ND, The link is below: