"It's odd," said Peaches, "but we didn't know the shadows were there until we had the light."
One of the younger rats timorously raised a paw.
"Um... and even when the light has gone out, we know the shadows are still around," she said.
"So now you're not just frightened of things that you can see and hear and smell, but also of things that you can... sort of... see inside your head. Learning to face the shadows outside helps us to fight the shadows inside. And you can control all the darkness." Dangerous Beans, p. 46
"Even though my body is shaking, I can keep a place free from you. I can feel you running round in my head, you see, but all the doors are closed to you now. I can control the shadows inside which is where all darkness is. I am more than just a rat. If I am not more than just a rat, I am nothing at all." Dangerous Beans, pp 263-4
Terry Pratchett. The Amazing Maurice and his educated rodents. New York: Harper Trophy. 2001.