Dividing America into two mutually incomprehending tribes is a familiar device for understanding this vast and diverse nation. We've had the North and the South, the East and the West, the red states and the blue states. Until this week, another important split was between Main Street and Wall Street.

For more than a year, Wall Street has been gripped by a severe credit crunch that pessimists such as George Soros warned was the most severe financial crisis since the Great Depression. Main Street wasn't unscathed - the jobless rate shot up, house prices fell and foreclosures mounted. But the hoi polloi kept their cool, thanks in part to a fiscal stimulus that prompted the US economy actually to grow 3.3 per cent in the second quarter of this year.