The horizontal bar represents your understanding of what is best. It is your model of the character of Christ. It consists of what an ideal person would think, feel, and do in every situation, according to your present understanding. It is the standard to which you are held accountable.
The bar of justification can be thought of as akin to a finish line, in the sense that your relationship with God begins a new phase as soon as you reconcile to what you know about him, albeit that finish line is itself the start of the path of learning more about him. As you learn more about God, remaining justified requires you to immediately reconcile yourself to anything you learn, as depicted in Lehi’s vision of the tree of life,1628 where pilgrims had to maintain a grip on an iron railing as they walked along it.