"An ignorant person is one who doesn't know what you have just found out.

It isn't what we don't know that gives us trouble it's what we know that ain't so.
It isn't what we don't know that gives us trouble it's what we know that ain't so.
It isn't what we don't know that gives us trouble it's what we know that ain't so.
It isn't what we don't know that gives us trouble it's what we know that ain't so.