Hmm. I thought that was too easy. After I typed that quote below, I started wonder about the attribution. I didn't think it was President Lincoln who said those wise words. I searched around a bit and found that the quote has been attributed to:
- Mark Twain
- Albert Einstein
- George Eliot
- Groucho Marx
- Proverbs 17:28 Even a fool, when he holdeth his peace, is counted wise: and he that shutteth his lips is esteemed a man of understanding.

When I first heard the saying, it was my dad giving me a valuable piece of advice. So, in a way, I always attribute the quote to my dad. I guess that puts him in good company.