ABSTRACT
You have all no doubt experienced the exasperation or perhaps the mortification of having someone else, with seeming ease, spot a problem in a drawing of yours and sketch a solution for you. “Why couldn't I have spotted that?” you say. Well, you can spot it, though it's not so easy after you've drawn it, for your eyes have a tendency to cover up for your shortcomings by finding some false logic to convince you it's okay.
