When I was in grade school, my mother was a graduate student in philosophy, and I learned from her about the categorical imperative. What I grasped at that impressionable age was that if you are thinking about doing something, you should imagine that everyone around you, even everyone on earth, will do the same thing. Because if you have the right to do it, then, of course, so does everyone else. I immediately saw that I should not throw my gum wrapper out the car window. If everyone did that the air would be thick, the ground covered, with foil and paper.