This painting is a good illustration of the relationship between Scripture and the Church. Saint Luke is writing the gospel, but he can only do so as he contemplates Our Lady and Our Lord. In other words, the inspired written Word of God is the product of a deep contemplative relationship with the incarnate Word of God. See how the picture is composed? The two pillars may be the two testaments: Mary and her Son the final fulfillment of the Old Testament. Luke representing the perspective of the New Testament–looking to Jesus the author and finisher of our faith.
The Blessed Mother, offering us her Son for contemplation is also an image of the Holy Mother Church. As Mary brings forth the Word of God incarnate, so Holy Mother Church brings forth the written Word of God. As the Mother of God offers the her Son–the Gospel of God–so Holy Mother Church conceives, gestates and gives birth to the written Word of God–the Gospel.
There is more: just as Mary is now Queen of Heaven, continually bringing forth the Word of God for the world through her ministry of intercession and praise, so Holy Mother Church continues eternally and in this present moment to bring forth the Gospel of God, preach the Gospel of God and interpret the Gospel of God for a needy world.
Finally, look at the man and woman in between the pillars on the bridge. There they are in the city looking away from the wonder of God’s revelation. Oblivious to the woman, the child and the scribe, they are entranced with one another and the distant scene that is cut off from the mystery and the miracle of Immanuel-God with us.