A few weeks ago, the day after he testified in Washington before the Financial Crisis Commission, I heard former Citigroup ( C) CEO, Chuck Prince, speak to a friendly business audience at a closed-to-the-business-press luncheon. I went into the meeting thinking Chuck Prince was a fool; one of the poster boys for the out-of-touch Wall Street CEOs whose actions helped bring the world economy to the brink of collapse two years ago. I left the luncheon with a much more nuanced view of the man.Prince raised some interesting questions that I -- and I suspect many -- would have a hard time answering, making me concerned about how much we've really learned. Prince was criticized by author Michael Lewis and others for his quote, "When the music is playing, you have to get up and dance and we're still dancing." That was his explanation, in early 2007, for why Citigroup was so heavily invested in the subprime mortgage space. It would be easy to write off Prince as a buffoon; someone in over his head. He was a lawyer, after all. He should have know better. People who make big mistakes in business are either idiots (like Prince), unethical (like Skilling or Kozlowski), or evil (like Madoff). We write them off, and move on. So the obvious question for Chuck Prince is, what the hell happened to almost kill what was once thought of as the world's leading bank? According to Prince, they held $40 billion in super-senior tranches on housing assets. Alan Greenspan had referred to these assets as "as safe as U.S. Treasuries." Overnight, they went from AAA to junk, according to the ratings agencies. At first, Prince (and his CFO Gary Crittenden) thought it was a $200 million problem. Then, it became an $8 billion problem, then an $11 billion problem, and later back to an $8 billion problem. By the time it was settled, however, Prince was long gone. It's clear that Prince seethes at the ratings agencies' role. Since his world changed overnight -- with AAA assets becoming junk -- Prince obviously believes he deserves some understanding. At one point in the luncheon, he said: "I guess what you should take from my story is, don't trust conventional wisdom. Even if the Federal Reserve chairman says some asset is rock solid, don't take his word for it. I guess in 2006, I could have gone down to our trading desk at the tip of Manhattan and told the traders, 'You know guys, I just don't think Greenspan or anyone else knows what they're talking about in reference to these super-senior tranches. I know we're at the top of the pyramid to always get the cash flow from these products, but I just think the world is going to change. Sell them all.' They would have looked at me like I'd lost my mind. They would have wondered, what does this lawyer think he's talking about?"