Knowledge is to know what one knows and what one does not know?

Answer 1

I'll take a stab at it: This seems to mean that it is a high order of knowledge to have a sense of the limits of one's knowledge. Being 'smart' and 'informed' or 'savvy' is great, but being aware of one's areas of ignorance, limits of skill and areas of doubt is a very important kind of knowledge indeed. People can be glib and persuasive, skilfully using rhetoric and half-backed information to get others to believe them. The wiser, scarier and much more costly approach is to be willing to shed light on ignorance, even if it is our own. No one finds this easy; few develop it as a strength.

Answer 2

You never know what you know unless you know it which is what you know but then you know it and you wouldn't question what you know would you? unless you don't know if what you know is true. but that's a different story.