There is something odd -- and dare I say novel -- in American politics about the crowds that have been greeting Barack Obama on his campaign trail. Hitherto, crowds have not been a prominent feature of American politics. We associate them with the temper of Third World societies. We think of places like Argentina and Egypt and Iran, of multitudes brought together by their zeal for a Peron or a Nasser or a Khomeini. In these kinds of societies, the crowd comes forth to affirm its faith in a redeemer: a man who would set the world right.

As...