Unlike we poor, simple twenty-first century types, the Christians of late antiquity / the early middle ages (take your pick) could hold more than one idea in their heads at the same time. So today we have essentially ended up with three observances in one: what the early Roman sacramentaries called "the Octave of the Lord," (indeed the greater part of the Mass was of the octave of Christmas) Various parts of the Mass and the Office also celebrate the divine motherhood of Our Lady Mary. Today’s "third feast” celebrates the Circumcision of Christ which has been celebrated since the sixth century. As today's Gospel relates, eight days after His birth Christ underwent, like all Jewish males, the rite of circumcision given to Abraham by God as a sign and pledge of his faith, and He received the Name of Jesus, "the name given by the angel before he was conceived in the womb."
May the prayers of Our Lady be with us in what promises to be a not uneventful time!