The tongue is our most powerful weapon of manipulation. A frantic stream of words flows from us because we are in a constant process of adjusting our public image. We fear so deeply what we think other people see in us that we talk in order to straighten out their understanding. If I have done some wrong thing (or even some right thing that I think you may misunderstand) and discover that you know about it, I will be very tempted to help you understand my action.
Silence is one of the deepest disciplines of the spirit simply because it puts the stopper on all self-justification. One of the fruits of silence is the freedom to let God be our justifier. We don’t need to straighten others out.
Source: Seeking the Kingdom