I'm watching Barack Obama speak in Chicago on election night of Super Tuesday. A year ago I was in Springfield, Illinois, watching him declare his candidacy for president on a frigid, windswept morning. The distance he has come is truly astonishing. "What began as a whisper in Springfield," he just said, "is now a chorus that cannot be deterred, for this campaign IS different."

When it comes down to it, the difference between Obama and Sen. Hillary Clinton is less about specifics-though they matter-than about emotion, language, tone and approach. His is a summoning to a higher cause in the name of history, using the cadence of poetry and the pulpit. Hillary, by contrast, is all about three-point plans and legislative language in the service of what they call "constituent service."

Obama calls his campaign a movement. He says we need to get over our fear. The subtext is: I am change, go for it. He talks about what people can do-do for themselves-rather than what government can do.

Both are valid arguments for Democrats. It is a close race, between poetry and prose. The conversation continues.