 Pointing out this error is one of the first things a market advocate would tell an interlocutor who committed the error. Frederick Bastier's wonderful What is Seen and Not Seen, the parable of the broken window, taught the lesson in reverse. He showed that an obstacle, a broken window, prevented a shopkeeper from acting as he would have acted, but for the need to overcome the new obstacle, that is, the need to buy a new window.