Have you ever walked alone in the dark, feeling like there's some thing out there in the darkness... You feel afraid, with the hairs all over your body standing on end, but you don't know why. You walk on, looking around; you see nothing, hear nothing, and you hope nothing is there. Your senses are on edge, everything straining to see or hear whatever it is that might be there.

But there's nothing.

When you finally get to where you're going, you find it difficult to walk. You feel like giving way to the mad panic lurking just beneath the surface of your self control, demanding that you run for the door, for safety. Fighting back the fear, you make your way indoors, thankful to be out of the darkness. You shut the door behind you and hope that nothing bangs against it.

You sigh with relief as nothing does.

Have you ever seen something move out of the corner of your eye - a flash and it's gone - but when you look around there was nothing there? Did you imagine it? Or maybe... maybe you saw the flash of something that only exists on the edge of your perception.

What is it that flashes past the edge of your vision, a glimpse of something that's not really there?

What follows you as you walk the darkness? What is it that is out there, where you can't see it but you know it's there?

What is it?

Have you felt it? Do you know what it is?