In a world where the celebration of holidays seems to begin earlier and earlier, the season of Advent is easily overshadowed by the high Feast of Christmas. It is often looked at as a sort of “build up” to or part of Christmas, rather than a season in its own right. But Advent is more than just a convenient way to count down the days until the Feast of the Nativity. Historically speaking, Adventide is about preparing for ALL of Christ's Advents.
The English word “advent” is borrowed from the Latin adventus, which simply means “a coming, approach, arrival.” Understanding Christ’s Nativity as His “First Advent” helps us understand why the season has become so integrally connected with Christmas. This connection can be clearly seen by looking at the propers prescribed in the historic Lectionary, such as the Communio ("The virgin shall conceive and bear a Son, and shall call His name Immanuel" [Isaiah 7:14]) and Offertory (“Hail, [Mary], highly favored one, the Lord is with you; blessed are you among women, and blessed is the fruit of your womb, [Jesus Christ]” [St. Luke 1:28, 42]) for Rorate Coeli, Advent's Fourth Sunday. Another subtle reference can be seen in the Introit Antiphon of the same Sunday, where the "Righteousness" and "Salvation" referenced are Christ (these nouns are actually capitalized in the traditional missal, to indicate their reference to the Divine). When you read it in that context: “You heavens above, rain down Righteousness; let the clouds shower It down. Let the earth open wide, let Salvation spring up" (Isaiah 45:8); you can see that it's talking about Christ's Incarnation. In fact, I believe the wonderful Advent hymn, "O Savior, Rend the Heavens Wide," is directly referencing this Antiphon and theme.
Interestingly enough, Christ "rending the heavens wide" can have a dual meaning, that being His Second Advent (or the Parousia [Παρουσία], a Greek word that, incidentally, is translated into Latin as adventus), which is one of the primary causes of our preparation in Advent. Indeed, the historic Roman Gospel reading for Ad Te Levavi, the First Sunday in Advent, reminds us that we “will see the Son of Man coming in a cloud with power and great glory” (St. Luke 21:27). In this context, Adventide is about preparing for Christ’s Second Coming - it reminds us to be vigilant like wise virgins (tying into the traditional Hymn of the Day for Ad Te Levavi, “The Bridegroom Soon Will Call Us”). This also explains the penitential aspects of the season. Christ’s Second Advent is a somber occassion - one of joy for the believer, to be sure, but one that must be tempered by vigilance and repentance (“watch and pray, so that you do not fall into temptation”). This is why we omit the Gloria in Excelsis during this season. It also helps make sense of the other reading on the first Sunday. The Epistle tells us to "put off the deeds of darkness" because "the day is almost here" (putting off the deeds of darkness is expressed throughout much of Advent hymnody); as pointed out above, the Gospel makes clear what Day that is: The Coming of the Son of Man on clouds of Glory.
The Adventide bridge between Christ's First and Second Coming is the Third Sunday, Gaudete, which means "Rejoice." The "rejoice" theme is repeated throughout the propers on the Third Sunday. In fact, St. Paul's famous Philippians passage, "rejoice in the Lord always," constitutes the historic Introit Antiphon AND Epistle reading. The emphasis of this theme stems from the day's liturgical nature as a sort of break from the fast of the Advent season. The parament color is rose, a combination of the penitential violet of Advent and the jubilant white of Christmas. This highlights why I view it as a "bridge" between the aforementioned Advents; while it isn't a full celebration of Christmas, it is a time for rejoicing!
But we've still only focused on two of Christ's Advents. What I like to call the "third" Advent is none other than Christ's Present Advent in the Holy Supper. Luther's little Catechism highlights the preparedness we should have for Christ's Advent in the Sacrament, which is really the same preparation that we should have for Christ's other Advents: Repentance and faith that believes His promises. This is why many of the propers throughout the season, like Populus Sion (the Second Sunday)'s Communio and Gradual, tell us to "behold the joy and salvation that come to us;" that God will come to save His people and "gather His holy ones to Himself" (Psalm 50:5). He has already and will continue to do this, in the Blessed Means of Grace. In the Holy Supper He comes to us and abides with us, not by our choice or by human means, but - just as in His other two Advents - by the power of God.
Advent is all about being prepared for the coming of Christ. It is no wonder that St. John the Baptist occupies so much of the focus in the historic Gospel readings ("Prepare the Way of the Lord"). May we all take heed of that voice in the wilderness crying and be cognizant of Christ's First Advent in Bethlehem, His Present Advent in the Holy Eucharist, all as a foretaste of His glorious return. May we all be prepared for that Second Advent when He shall come on the clouds of heaven with all the Holy Angels to restore the cosmos by the power of His mighty hand, that we whose names are written in His Book of Life may live and reign with Him forever where sorrow is no more.