The Immaculate Conception - From the acts of Pope Pius IX

The fact that the Virgin Mother of God had at the moment of her conception triumphed over the foul enemy of man, hath ever been borne out by the Holy Scriptures, by the venerable tradition of the Church, and by her unceasing belief, as well as by the common conviction of all Bishops and faithful Catholics, and by marked acts and constitutions of the Holy See. At length the Supreme Pontiff Pius IX., in compliance with the wishes of the Universal Church, determined to publish it as a truth of faith, on his own absolute and unerring authority, and accordingly, on the 8th day of December, 1854, in the Vatican Basilica, in presence of a great multitude composed of the Fathers Cardinals of the Holy Roman Church, and Bishops from all parts of the earth, he, with the consent and jubilation of the whole world, declared and defined as follows That doctrine which declareth that the most blessed Virgin Mary was in the first instant of her Conception preserved, by a special privilege granted unto her by God, from any stain of original sin, is a doctrine taught and revealed by God, and therefore is to be held by all faithful Christians firmly and constantly.