Wisdom

We often say that age is wisdom. That those who have lived long enough have acquired a knowledge that is more than self--that has come with experience. I say age is not wisdom. The young, too, are capable of wisdom...often without the judgment and prejudice that age can teach. Age brings experience, and once you get enough of it, people begin to believe you.
With age comes reputation...and if that reputation is a favorable one, we consider the possessor full of wisdom...and we consider ourselves wise in listening.
Confidence comes from reputation, also. Confidence moves from arrogance when reputation is formed.
Once someone has proven themselves, then they can say what they believe to be true. Then they can say what they know--and have perhaps always known, though no one would listen. Then they can be wise.