It is hard to know what you do not know...
A teacher of mine once sent a report home to my father saying 'jacqueline knows far too much about things she shouldn't know about at all at her age , and not enough about what we are trying to teach her!
Maybe you challenged your teacher more than she challenged you!
The more you know the more you understand how much you do not know.
This is a true statement.
The trouble is, too many people are not aware of their lack of knowledge and act as if they do know everything. That makes them dangerous.
Agreed, that is the pupose of this statement. Even the books from which we learn have inaccuracies.