The premise is that there are two types of interpersonal changes: changes that you cause to others, and changes that others cause to you.
The are two main ideas that are presented. The first is that an external changer or strong willed person, a president, a general, a CEO, or some other sort of leader, would cause many changes in others while experiencing few changes themselves. The second is that an internal changer or a weak willed person, such as an average joe working a desk job, is unable to cause changes in others while constantly being changed themselves. There are a few well established analogies of this system (the worst of which is the shepherd/sheep analogy).
Here are my thoughts: while the external changers (CEOs, etc.) are generally viewed as the best way to go, I see the inability or reduced ability that many of them have to internal changes as a monumental deficit. If you can't be changed by others, you are unable to learn or grow as a person, at least the way I see it. Yet if you allow yourself to be changed too much or too often, you lose some ability to change others, similar to a substitution effect.
The question that has been bugging me is how to manage these two behaviors. Is there a constant equilibrium point on the scale that is the most effective? Are there multiple such points? Or is an oscillatory cycle between internal and external behavior more effective?