"My friend Richard Feynman said, "I don't know." I heard him say it several times. He said it just like Harold, the mentally handicapped dishwasher I worked with when I was a young man making minimum wage at Famous Bill's Restaurant in Greenfield, Massachusetts. "I don't know" is not an apology. There's no shame. It's a simple statement of fact. When Richard Feynman didn't know, he often worked harder than anyone else to find out, but while he didn't know, he said, "I don't know." I like to think I fit in somewhere between my friends Harold and Richard. I don't know. I try to remember to say "I don't know" just the way they both did, as a simple statement of fact. It doesn't always work, but I try."