maybe not a favorite, but interesting:
HE WHO KNOWS
He who knows not, and knows not that he knows not, is a fool, shun him;
He who knows not, and knows that he knows not, is a child, 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.
-Persian Proverb