According to the tradition received from the earliest centuries, Joachim and Anna, in thanksgiving for the child God had given them, brought the young Mary to the Temple in Jerusalem and dedicated her to God. The feast keeps this dedication: the girl who would become the living temple of God is herself given to the house of God.
The hymns dwell on the wonder of it, that she who would contain the Uncontainable is led, as a small child, into the holy place, and prepared there in prayer for the vocation no other human being has borne. The feast is not chiefly about a historical detail but about consecration: a life set apart for God from its earliest years.
The Entry falls on November 21, within the Nativity Fast, and the Church begins on this feast to sing the hymns of the coming Nativity, for the one dedicated in the Temple is being prepared to give the world its Saviour. It is the dawn's first light before the feast of the Incarnation.