Pope Pius IX, in Ineffabilis Deus in 1854, defined the Immaculate Conception as the belief that "the most Blessed Virgin Mary was, from the first moment of her conception, by a singular grace and privilege of almighty God and in view of the merits of Christ Jesus the Savior of the human race, preserved immune from all stain of original sin...."
For more on the Immaculate Conception, read Fr. William Saunders here, or David M. Bristow here.
Scripture readings and prayers for December 8 can be found on the U.S. Conference of Catholic Bishops website here. [Image: Madonna Window, USCCB website.]
CLARIFICATION on obligations:
SATURDAY, DECEMBER 8, 2018 - THE IMMACULATE CONCEPTION OF THE BLESSED VIRGIN MARY: December 8, the Solemnity of The Immaculate Conception of the Blessed Virgin is always a day of obligation except in years when December 8 falls on a Sunday and the solemnity is observed on December 9. Therefore, Saturday, December 8, 2018 IS a Holy Day of Obligation.
OBLIGATION TO ATTEND MASS:
As occurred last year at Christmas, we again have the unusual occurrence of the obligation of the people to attend Mass on two consecutive days. Can a person satisfy two obligations with one Mass? It has been clarified by the United States Bishops’ Conference of Catholic Bishops Committee on Divine Worship that "When consecutive obligations occur on Saturday-Sunday or Sunday-Monday, the faithful must attend Mass twice to fulfill two separate obligations."
Therefore, the people are to attend one Mass for the Solemnity of the Immaculate Conception (from Friday evening through Saturday the 8th), AND a Mass for the celebration of the Second Sunday of Advent (from 4pm on the 8th through Sunday the 9th).