If I had to use one word to describe light, I would use the word "radiance." There's a brilliance and a sense of direction that comes from light.
If you are in a totally pitch-dark room and there's the smallest element of light, then that light chases darkness. But the darkness cannot overrule the light. So associated with light is a warmth. Associated with darkness is a coolness that I think is very significant.
The Light of Christ is what many people would call a conscience. But it's more than a psychological effect that takes place within people. Someone can be riding on a bus, see someone in distress, and feel a compassion and a desire to assist and serve this person.
Many people would say, no, that's just natural behavior. But it's more. It is the influence of God that pulls us, that influences us to be good and to do good. Every person ever born in history, now, in the future, is influenced by the Light of Christ for goodness. As we yield to that influence to do good and become good, then the Light of Christ increases within us. As we disobey, light is decreased and can ultimately be diminished.
Patterns of Light: The Light of Christ
What is light? In this three part series, Elder David A. Bednar discusses how we receive and perceive light from God. Part 1 centers on the properties of light and how the Light of Christ affects all men and women everywhere.