From the introduction:
Even adults are brave only in the light. They spend their lives dashing from halo to halo, grasping for torches and light switches. They don't linger in the shadows, for in them could be anything. And every night they send even the youngest of us into that darkness, alone and unprepared.
They do this because they know there really are things in the darkness. Things hungry for fear. Our parents fill the darkness' bellies with the ripest, most swollen fears, so the darkness leaves them alone. Or perhaps they think that if the monsters eat our fears, we will become brave and grow up. Whatever the case, their pact is made. The darkness is fed. And we children eventually stop screaming.