On page 362 of the book there is a quote I came across I really liked. "Rather know nothing than half-know much! Rather be a fool on one's own than a sage according to the opinion of others!" What I think this is saying is first of all it is better not to know about something than just to know just a little bit. And the second part means it is better for you to be up front about not knowing something than it is to pretend that you know about it and have people believe falsely that you know a lot about it when you really don't.
[Lightly edited to enhance readability -TT]