The word “Advent” stems from the Latin word adventus, which literally means “coming” or “arrival.” Primarily this refers to the first coming of Jesus on Christmas day.
However, the season of Advent is also focused on two other "comings" of Jesus.
St. Bernard of Clairvaux wrote a beautiful summary of these three comings of Christ that is featured in the Church's Office of Readings during Advent.
To simplify St. Bernard's summary even further, it can be explained as follows:
St. Bernard continues with his explanation of these three comings, focusing on their connection.
This "middle" coming is Jesus' arrival into our own lives. The Church often explains this to be through the sacraments, in particular through Baptism and the Holy Eucharist.
It not a "physical" coming, but a spiritual one, where Christ comes to dwell within our souls.
Each Advent we are challenged to prepare for all three comings of Christ, celebrating his birth, while also preparing our heart to receive him now and at the end of time.
