It takes a smart man to know when he's stupid. --

Related:

• It takes a smart person to know that the person is
  stupid...
• Man will survive into eternity.
  He's too stupid to know when he's beaten...
• The military is developing artificial intelligence because that way they can have the perfect fighting man -
  smart enough to understand what he's been told to do...
• Burns: The whole plant is environmentally sound. It's powered by old newspapers,
  machinery is made entirely of used cans, and the...
• It takes a big man to admit when he's wrong, and an even bigger one to keep his mouth shut when he's right.
  - Jim...
• A man gets what he wants by acting smart; a woman,
  by playing dumb...
• When a stupid man is doing something he is ashamed of,
  he always declares that it is his duty. -- George...
• Bart: We know who you are, Ms. Botz. Or should I say,
  Ms. Botzcowski. You're the Babysitter Bandit...
• The most hopelessly stupid man is he who is not aware
  that he is wise...