To the happy congregation in Barack Obama’s church of fervid believers, the presumptive Democratic nominee for US President is like none that has ever come before him. The soaring oratory, delivered at vast rallies that can seem unsettlingly fascistic at times, hails a new dawn in American politics.

“We are the change we have been waiting for!” he cries. To which the multitudes respond repeatedly with idolatrous passion, if not much of an ear for grammar: “Yes We Can!”

But for all the excitement generated by his undeniably impressive campaign, for all the novelty of his youth, his very recent emergence to national prominence and, of course, his ethnicity, the Obama phenomenon is just another manifestation of a well-mined tradition in American politics. A capacity for reinvention is central to the American spirit, in politics as in economics, and conjuring the aura of change to orchestrate an organic and peaceful overthrow of the existing order has long been essential to the nation’s success.

What really marks America out though, is that it is only in the United States that, every decade or so, a political leader emerges literally from obscurity to seize the national spotlight.

In parliamentary systems, politicians audition for long years on the national stage. Tony Blair and John Major were both considered quite fresh when they became Prime Minister, but they had been in parliament for 14 and 11 years respectively, and both had held prominent national political positions for years.

In America, by contrast, thanks to an oddly lopsided primary system that favours small, rural states over large urban ones and the virtues of personal contact over mass, televised communication, you can, given the talent and the right political circumstances, when the yearning for change is strong enough, bypass all the usual required routes and go straight to the top.