The Immaculate Conception Proclaimed, 1854

In the Constitution Ineffabilis Deus of 8 December, 1854, Pope Blessed Pius IX pronounced and defined that the Blessed Virgin Mary “in the first instance of her conception, by a singular privilege and grace granted by God, in view of the merits of Jesus Christ, the Saviour of the human race, was preserved exempt from all stain of original sin.” Check out this clip from Youtube:

(From the 1911 Catholic Encyclopedia)