" She was the only one left, and she was real.
To be the only one, and to know that you are real - that's sanity, isn't it?
But just to be on the safe side, maybe it was best to keep pretending that one was a stuffed figure. Not to move. Never to move. Just to sit here in the tiny room, forever and ever.
If she sat there without moving, they wouldn't punish her.
If she sat there without moving, they'd know that she was sane, sane, sane.
She sat there for quite a long time, and then a fly came buzzing through the bars.
It lighted on her hand.
If she wanted to, she could reach out and swat the fly.
But she didn't swat it.
She didn't swat it, and she hoped they were watching, because that proved what sort of a person she really was.
Why, she wouldn't even harm a fly... "

― Robert Bloch , Psycho (Psycho #1)