My eight year old daughter asked me:

"Dad, what scares us? Why do we get scared when we suddenly see something like a shadow?"

I hoped she would understand what I was going to say.

"Well, I don't know. But, I think, something very similar to a human being and yet not human is what scares us, sweetheart. At least, the idea of it is what scares us the most," I said wisely.

She looked reflective for a second. And then she asked with this thrilling look on her face:

"Isn't that what we see when we look at the mirror, daddy?"

She had understood well.