You are the light of the world. A city on a hill cannot be hidden. It only takes a tiny light to illuminate the darkness. In scientific terms, darkness is nothing, light is something. Darkness is the absence of energy.
Light is the presence of energy.
In your life, no matter who you are or where you are, you carry the energy or spirit of Christ to all those around you. That spirit is passed on from person to person, illuminating the darkness of their lives. If we could track it, your transmission of Christ' spiritual light could be traced as traveling all over the world. When we face reality, each of us is critically important to God. We are important because we are His way of getting His love into the world.