Kirsten taped a poster to the ceiling, containing the text "CAN YOU READ THIS?" After George started mutilating her with a knife, she remembered the poster, looked up, saw the poster, but the text was illegible. She thought that proved she was dreaming, but I have read text in my dreams. You can argue that the book I was reading in my dream was not a real book, but how would I know that if I was dreaming? After I woke up, I remembered the dream and realized that I was not reading a real book, but I did not know that in the dream.