Why do we start teaching?

I wrote about the responsibility of rank in my last post, and then I discovered this fabulous post by Wayne Muromoto about teaching in budo, why we do it, why it's important.  He does a lovely job of talking about how the responsibility starts, and how we should accept it and shoulder it.

http://classicbudoka.wordpress.com/2014/01/13/106-becoming-sensei/