Appearance is something absolute, but reality is not that way - everything is interdependent, not absolute. So that view is very helpful to maintain a peace of mind because the main destroyer of a peaceful mind is anger.
One's appearance bespeaks dignity corresponding to the depth of his character. One's concentrated effort, serene attitude, taciturn air, courteous disposition, thoroughly polite bearing, gritted teeth with a piercing look - each of these reveals dignity. Such outward appearance, in short, comes from constant attentiveness and seriousness.