People, and others around them, may or may not have a sense for how close they are to success, at any given point in their effort. But because no one has a true bead on the future, they are as comparatively prone to make an error: in giving up, when in fact success is close, as Thomas Edison suggests; or in keeping at it, when in fact success is far away and perhaps no longer worth pursuing. It can be a tough judgment call in any given moment, but it is inevitably a choice that people have to make. The aim is to get it right, of course: keep at it, when success is close; or give up, when a particular success ought to be given up. I see both as viable choices.