Considering - "one with the special skill or knowledge representing mastery of a particular subject" as an expert and yet, to me, if the one that has such skill and knowledge has no tact they fall off the expert mountain. Having a great deal of mastery and cannot deliver it just blows it in my way of thinking. Also we see some are just an expert in their own minds and truly know very little about anything much.

How hard is it for us to learn anything from the experts when they are unable to share? Imagine a person that is an expert on engines, but cannot help you get your engine running. I am thinking "mastery" requires all aspects to be an expert. The day a man learns how to share (pay it forward) his great expertise with humility is a grand day for many may benefit. It is funny how when we are young we are experts on everything and when we get older we realize just how much we don't know about everything!