Solemnity of the Immaculate Conception of the Blessed Virgin Mary (Not obligatory)

Traditionally, the Solemnity of the Immaculate Conception, placed on December 8 is a Holy Day of Obligation. On this day we celebrate that the Virgin Mary was conceived without original sin, the corruption in our nature that makes our will deviate from what is right. This year December 8 falls on a Sunday in Advent which takes precedence and the celebration of the Solemnity is moved to Monday, Dec 9; however, it loses its obligation since it is so close to Sunday.