"To you, then, light is crucial. While you remain in darkness, the miracle remains unseen. Thus you are convinced it is not there. This follows from the premises from which the darkness comes. Denial of light leads to failure to perceive it. Failure to perceive light is to perceive darkness. The light is useless to you then, even though it is there. You cannot use it because its presence is unknown to you. And the seeming reality of the darkness makes the idea of light meaningless."
 

A Course in Miracles, Lesson 91