The violet-colored vestments worn during Advent may give an impression that the days before Christmas, like those of Lent, are a time of penance. In fact, they are a time of anticipation and preparation. The Catechism of the Catholic Church states, “the liturgy of Advent each year … makes present this ancient expectation of the Messiah” (No. 524), and the subdued colors of the season symbolize the darkness we must endure as we await the light and warmth that Jesus’s birth will bring into the world.
During Advent we do not use the Gloria at Mass, and this, too, may seem penitential. However, the Gloria is the hymn the angels sang to announce the birth of Jesus, so we simply lay it aside until we celebrate Christ’s birth at Christmas. In the meantime, however, we continue to sing the Alleluia.
The General Instruction of the Roman Missal (GIRM) mentions that Advent should be marked by a moderation suited to the character of the season without expressing prematurely the full joy of the Nativity of the Lord. This is an excellent summary of our belief: the happiness and joy of Christmas are not fully realized, so we observe the days of Advent with moderation and sobriety.