If you annoyed my little cousins, they will most likely come up to you and draw a cross mark with their index on the palm of your hands.. When they play House, they would trace a line on the ground with their tiny feet to divide their stuff..

Simply because in their world, an imaginary line or drawing has a certain finality that cannot be reckoned with. So you are forced to believe that it is there, when really, it is not there at all.