Related:

• He who knows, does not speak. He who speaks, does not know. -- Lao Tsu
• He who knows others is clever; he who knows himself is enlightened.
  -- Lao-tzu, Chinese philosopher and founder of Taoism...
• The good man is the teacher of the bad, And the bad is the material from which the good may learn.
  He who does not value the teacher, Or greatly care for the material, Is greatly deluded although he may be learned....
• He who knows that enough is enough will always have enough. -- Lao Tsu
• He who knows others is wise. He who knows himself is enlightened. -- Lao Tsu
• He who lives out his days has had a long life. -- Lao Tzu
• Who does not trust enough will not be trusted. -- Lao Tsu