In this world, when you open a skull, you won't find a brain, just another small skull inside, staring outwards in the direction of your eyes. You might think, the first time you do this, that you have found the very principle of thought, until curiosity forces you to open the second skull, and you discover that it isn't empty, but full with yet another bit of staring bone (so you look up, away from the mirror hole in the top of the skull you hold in your hands, your eyes half-closed as you try to find the ceiling somewhere above you).