[clwk]

The version of this I first heard in school was:

He knows not and knows not that he knows not is fool. Shun him.

He who knows not and knows that he knows not is a student. Teach him.

He who knows and knows not that he knows is asleep. Wake him.

He who knows and knows that he knows is wise. Follow him.

[perl4ever]

Someone said that the wise (person) knows that they know nothing.

I'd prefer to say wisdom is knowing what you know and what you don't, and it's much harder and more valuable than you might think.