Today will send a message more powerful than ever

Since the swearing-in of the very first president, George Washington, in April 1789, it has been the central event of the American national calendar - their equivalent of a coronation.

From the outset, the inauguration owed a great deal to the coronation rituals of the British mother country, complete with a solemn oath sworn on the Bible. But there were crucial differences: George Washington wore civilian dress at his inauguration - marking his status not as sovereign but as First Citizen - and that first inauguration took place not in a cathedral or court but on the balcony of New York's Federal Hall, one of a series of different locations in the republic's early days.

By the middle of the 19th century, the rituals of Inauguration Day were almost complete: the swearing of the oath alongside the new president's predecessor; the sonorous public address, steeped in patriotic clichés; the parade down Pennsylvania Avenue from the Capitol to the White House.

Occasionally, there were hitches: some outgoing presidents, such as John Quincy Adams and Andrew Johnson, refused to turn up to their successors' celebrations. In 1853 one new president, the former baker Franklin Pierce, chose to "affirm" his oath rather than swear on the Bible - something that would be barely conceivable in today's world of ostentatiously God-fearing politicians.

But it was in the last century, as the United States transformed from a republic into an empire and television beamed live pictures into the living rooms of millions, that Inauguration Day became a genuinely national ceremony. From FDR telling the crowds that they had "nothing to fear but fear itself" to JFK's summons to a "new frontier", from Jimmy Carter walking on foot to the White House to Ronald Reagan's multi-million-dollar Hollywood blowout, it has become more spectacular with every edition.

Today's ceremony, however, will be remembered long after many others have been forgotten.

For a black man to take the oath of office - once sworn by men who owned slaves - is an extraordinarily powerful moment. T he image of Barack Obama, one hand aloft, sends a resounding signal to victims of discrimination the world over.

For perhaps the first time, the inauguration does not just belong to America - it belongs to us all.