A journey whose ultimate destination is unknown

Why is it so difficult to give up old perceptions when it is clear that what we really know is only a fraction of what there is to be known? The tiny fraction we see is not the only way it is. Whenever we say, "I know it," it means that we no longer want to struggle with other ways of seeing it. But the way we once saw it may not be the way it is now. Certainly the way something is now does not determine that it will always be that way because we are, all of us, on a journey whose ultimate destination is unknown.