What Advent is, really, is a discipline: a way of forming anticipation and channeling it toward its goal. There’s a flicker of rose on the third Sunday—Gaudete!, that day’s Mass begins: Rejoice!—but then it’s back to the dark purple that is the mark of the season in liturgical churches. And what those somber vestments symbolize is the deeply penitential design of Advent. Nothing we can do earns us the gift of Christmas, any more than Lent earns us Easter. But a season of contrition and sacrifice prepares us to understand and feel something about just how great the gift is when at last the day itself arrives.
— Joseph Bottum, First Things
Read the whole EXCELLENT essay here