I am at a scientific conference being held in a large auditorium. I am sitting somewhere in the middle section when it is my turn to speak. I go to the front of the room and show my slides. Afterwards I sit down again, this time on the right-hand side of the hall. Looking among my papers, I find a book containing copies of all of the slides from all of the talks, including my own. One of my graphs is reproduced in a shiny metallic ink. "Oh, this is a good idea", I say to myself about the book.