I observe that each man has his individual view about the world that is different from other men's viewpoint. In other word, each man has his own concerns.
The point here is we can't change people. I have heard somewhere that we can't change people or influence them and I have believed those claims. But not now. We don't even change his own concerns. For example, if all a man cares about is money, you can't direct his thought to other issues.
Therefore I come to a conclusion that if I want to influence or persuade someone, I shouldn't just use my words because people won't believe in your words. Talk is cheap. Instead, I need to show him the side of the problem that I perceive.