Can't grasp credit crisis? Join the club.

"All these investments, of course, were highly risky. Higher returns almost always come with greater risk. But people — by “people,” I’m referring here to Mr. Greenspan, Mr. Bernanke, the top executives of almost every Wall Street firm and a majority of American homeowners — decided that the usual rules didn’t apply because home prices nationwide had never fallen before. Based on that idea, prices rose ever higher — so high, says Robert Barbera of ITG, an investment firm, that they were destined to fall. It was a self-defeating prophecy."