"Let the whole creation therefore sing praise and dance and unite to celebrate the glories of this day. Today let there be one common feast of those in heaven and those on earth. Let everything that is, in the world and above the world, join together in rejoicing. For today a shrine is built for the Creator of the universe. The creature is newly made ready as a divine dwelling for the Creator" (Office of Readings, The Birthday of the Blessed Virgin Mary)
Catholics are sometimes accused of mariolatry - i.e. of idolising Mary. This is untrue. We venerate the Blessed Virgin Mary, because she is the Mother of our Lord and Saviour, Jesus Christ. In the Apostolic Constitution, Ineffabilis Deus, written by Pope Pius IX in 1854 (incidentally four years before the Marian apparitions at Lourdes), we read that:
"the most Blessed Virgin Mary, in the first instance of her conception, by a singular grace and privilege granted by Almighty God, in view of the merits of Jesus Christ, the Savior of the human race, was preserved free from all stain of original sin, is a doctrine revealed by God and therefore to be believed firmly and constantly by all the faithful" (Ineffabilis Deus).
In other words, our Blessed Mother, was conceived without sin, because she was to become the Mother of God. In this way, she was the first person to be redeemed by the passion, death and resurrection of Jesus Christ (cf. Lumen Gentium 53, Dogmatic Constitution of the Church from Vatican II).
This may sound very heavy, but in simple terms, we honour Mary, because she is the Mother of Jesus, Our Lord God and Saviour. In the Divine Office for Morning Prayer we pray: "Lord, God, the day of our salvation dawned when the Blessed Virgin gave birth to your Son." Through Mary's fiat, her 'yes' to the will of God, Mary was to become instrumental in the salvation of the whole world. Mary teaches us to say 'yes' to God, what will your 'yes' to God's will for your life achieve in the story of salvation? What role will you have to play?