(A ruler) cannot and should not keep his word when to do so would go against his interests or when the reason he pledged it no longer holds.
Self-pity imprisons us in the walls of our own self-absorption. The whole world shrinks down to the size of our problem, and the more we dwell on it, the smaller we are and the larger the problem seems to grow. Awareness of others is a healthy antidote to this self-focus.