One of the ec 10 teaching fellows recommends this article
in Slate. Michael Kinsley asks, What motivates billionaires?, and in the process offers this summary of basic economics:
Even in its most primitive form, the invisible hand is a brilliant explanation of what motivates most of us, and how our efforts serve the common good. We work to produce things that can be traded for things we want. That trade makes us better off than we would be if we made everything we consume ourselves. The first exchange of one caveman's dinosaur meat for another's rather attractive decorative rock started a process that, after millions of years, leads to DVD players at Wal-Mart that cost less than DVDs. Or something like that.
By the way, Kinsley was an economics major at Harvard (and also editor of the Crimson).