Of all the elementary particles, the photon, the quantum unit of light, is the only one detectable with the ordinary senses. One photon, the smallest amount of light possible, is visible to the naked eye.
Jesus said, "You are the light of the world." (Matthew 5:14) It is our job to be light, to drive out darkness. Everything we do that adds to the light of the world helps to make it brighter, no matter how small the action.