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• He who knows how to be poor knows everything. -- Jules Michelet (1798-1847)
• He who knows not and knows that he knows not is ignorant.
  Teach him. He who knows not and knows not that he knows not is a fool....
• He that knows not what the world is, knows not where he is himself.
  He that knows not for what he was made, knows not what he is nor what the world is....
• A truly wise person knows that he knows not.
• He knows not how to know who knows not also how to unknow. -- Sir Richard Burto
• It's hard to argue with someone who knows what he's talking about.
• The whole world steps aside for the man who knows where he is going.