The fourth Sunday of Advent prepares us to welcome the Light of Christ into our world at Christmas. The spiritual principle of death to self is explained using a lamp lit by an extension cord as a demonstration. In Mass Christ offer's himself as the perfect sacrifice (pouring out of self). We can join ourselves to His sacrifice, thus purifying our offering by Christ's, and further dying to self, so that He lives more, His light shines more brightly, in us. And nothing can distinguish that light of Christ that is in us.