What others have said.

 
• A man said to the universe:
  “Sir, I exist!"
  “However,” replied the universe,
  “The fact has not created in me,
  “A sense of obligation.”
  -Stephen Crane
  
• Never confuse the true with the real.
  -Me
  
• Beware the floo-floo bird.
  -Frank Lloyd Wright
  
• The partisan, when he is engaged in a dispute, cares nothing about the rights of the question, but is anxious only to convince his hearers of his own assertions.
  -Plato, Dialogues, Phaedo
• To argue with a man who has renounced his reason is like giving medicine to the dead.
  -Thomas Paine, The Crisis
• "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man."
  -George Bernard Shaw
• "Ever tried. Ever failed. No matter. Try again. Fail again. Fail better."
  - Samuel Becket
• "He who seeks vengeance must dig two graves one for his enemy & one for himself.”
  -Chinese Proverb 
• Men never do evil so completely and cheerfully as when they do it from religious conviction.
  -Pensées 894, by Blaise Pascal
• Faith is the surrender of the mind; it's the surrender of reason, it's the surrender of the only thing that makes us different from other mammals. It's our need to believe, and to surrender our skepticism and our reason, our yearning to discard that and put all our trust or faith in someone or something, that is the sinister thing to me. Of all the supposed virtues, faith must be the most overrated.
     - * "Holier Than Thou", Penn & Teller: Bullshit!, 23 May 2005
• “Live a good life. If there are gods and they are just, then they will not care how devout you have been, but will welcome you based on the virtues you have lived by. If there are gods, but unjust, then you should not want to worship them. If there are no gods, then you will be gone, but will have lived a noble life that will live on in the memories of your loved ones.”
  -- Marcus Aurelius