Knowing about not knowing is the worst kind of knowledge

I’m not the most intelligent or the most knowledgeable person in the office, much less the entire nation, world or the universe. So obviously, there are so many things that I don’t know about. And the fact that there are many things that I don’t know about never really bothered me much.
But watching the movie “Changeling” on the HBO tonight makes me wonder about those things that I know I don’t know.
The movie tells the story of a mother who was looking for her son. Until the very end, her knowledge that she didn’t know what happened to her son kept her going and hopping and believing that her son is still alive.
And now it gets me thinking about all those things I know I don’t know like… where in the hell did I left my red Zippo lighter?
It’s not like you forget something. Cause when you forget something; you’d rake through your brain and find a grey or blackened area. Something is there, but you just can’t make heads or tail of it.
But when you know you don’t know, you’d rake through your brain and find a hole, a void that is just empty. Cause there is nothing there is nothing there in the first place.