Like it's Jewish predecessor, the Catholic calendar is built around the natural cycles of life: the daily, monthly, and annual cycles that we see year after year. That is why our calculation of Easter uses a combination of solar and lunar cycles and and choice of December 25, is not based on a belief that Jesus was born in December but is symbolic.
From now until December 21, every day will get darker and darker until December 21 the darkest day of the year. How do we as Christians respond to the ever increasing darkness? Are we afraid of the dark? Do we sink into depression? No, we light a candle. And with every darker week, we light another candle. This year, dec 1, dec 8, dec 15, and dec 22 we light another candle.
And on December 25, as the days begin to grow brighter we proclaim the prologue to John's gospel
this life was the light of the human race; the light shines in the darkness, and the darkness has not overcome it
Bring on the darkness. We remain fearless. In today's second reading reading St. Paul tells us to "put on the armor of light."
Today as we start a new liturgical cycle it is time for us decide. This year let us be children of light in the darkness. At home, at work, every day let us be the one who bring the light. At the end of each day, we should be able to look back and name at least one time during that day when we brought light.