So, here at the library, we have a magic shelf called "The White Shelf." You put things on "The White Shelf" when they've been processed downstairs, and they are ready to head upstairs to the Circulation Desk to check in. It could be called "The Lazy Shelf" because you stick stuff there to avoid running up the stairs to drop stuff off. And, in truth, most of the shelves around here are white.
I was just showing a new employee where "The White Shelf" was, and explaining how lately, there seem to be two "White Shelves." I explained my system was to use whichever shelf already had books on it. My desk neighbor Carol overheard my explanation and giggled. I asked her which shelf she thought really was the True White Shelf. She said that was something we should probably decide. I agreed, and said that when we decided, we could stick a sign on the non-true White Shelf that said "This is not the white shelf."
"It would be like a Magritte painting," I said. "Ceci n'est pas the White Shelf." Carol looked at me for a moment, and then we both realized, "Nope. If we're going to be Magritte about it, we have to put the Ceci n'est pas the White Shelf sign on the shelf that actually *IS* the True White Shelf." Ah. Nothing wraps up the work day like a little dorkdom.