The Feast of the Immaculate Conception celebrated today is about the dogma pronounced by Pope Pius IX in 1854. He declared that through the merits of Jesus Christ, Mary was "preserved exempt from all stain of original sin" from the first moment of her conception.

This was possible through Jesus' choice to become human, and was part of God's plan for the salvation of all humankind.

The liturgical readings for the day reflect this. The First Reading from Genesis tells of the fall of humankind, and the role played by Eve. Here is foretold the coming of the new Eve, Mary. As part of God's plan to save the world, from this very beginning, Mary was the one who would fulfill the role of 'crushing the serpent's head', i.e. she would be the mother of the Saviour.

In the Second Reading from Paul's letter to the Ephesians, he reveals God offering salvation to humankind in the form of Jesus Christ as part of His deliberate plan: "He chose us, chose us in Christ... to become his adopted sons through Jesus Christ."

Then in the Gospel passage from Luke, we have the archangel Gabriel announcing to Mary that she was highly favoured in having been chosen by God to bear His Son. Again, the plan is unfolded further with Mary agreeing to be the willing instrument of His plan for humanity's salvation.