Dean Koontz said this quote

In this world where too many are willing to see only the light that is visible, never the Light Invisible, we have a daily darkness that is night, and we encounter another darkness from time to time that is death, the deaths of those we love, but the third and most constant darkness is with us everyday, at all hours of every day, is the darkness of the mind, the pettiness and meanness and hatred, which we have invited into ourselves, and which we pay out with generous interest.