She'd thrown something at the mirror, and then the mirror broke into a thousand pieces and she knew that wasn't all; she was breaking into a thousand… - Robert Bloch

Once you began speculation about that, once you admited to yourself that you didn't really know how another person's mind operated, then you came up against the ultimate admission — anything was possible.

Horror is the 'removal' of masks.

Norman Bates heard the noise and a shock went through him. It sounded as though somebody was tapping on the windowpane. He looked up, hastily, half prepared to rise, and the book slid from his hands to his ample lap. Then he realized that the sound was merely rain. Late afternoon rain, striking the parlor window.