On Wednesday, the 44th President of the United States will deliver a speech from the steps of the Lincoln Memorial in Washington.
In political terms, it won't be the most important address he has ever made. It isn't expected to unveil any radical new initiative or signal any change in policy. But it will resonate powerfully nonetheless, because of the identity of that President - Barack Obama, the first African-American to sit in the Oval Office - and the historical event it recognises: the 50th anniversary of Martin Luther King's I Have A Dream speech.
Delivered from those same steps around 3pm on August 28 1963 to a crowd of around 250,000, King's words are now regarded as one of the most significant pieces of oratory ever and came during the March On Washington For Jobs And Freedom. It was, as the history books tells us, a defining moment in the American civil rights movement and within two years, Congress had passed the 1964 Civil Rights Act and the 1965 Voting Rights Act. As a young man and, later, as a civil rights lawyer in Chicago, Obama would have been acutely aware of its significance.
But while King's speech was carried live on television (John F Kennedy watched in the White House) and widely reported in the following days, the insistent refrain he introduced towards the end was slow to become its defining element. Some newspapers didn't even remark on it. In part, this was because King had used the same metaphor in different speeches before. In part, because it was a departure from the script. It was a shouted admonition from gospel singer Mahalia Jackson, who had performed I Been 'Buked And I Been Scorned from the same podium and was still standing nearby, which caused King to move his script to one side and prepare to ad lib. "Tell 'em about the dream, Martin," she had said. So he did.
America will honour the past on Wednesday and laud the achievements of the civil rights movement. But its thoughts may also turn to the present, and to the state of racial relations in the US. And in delivering his own speech, the 44th President may return to the theme of an address he gave in the wake of George Zimmerman's acquittal for shooting dead unarmed 17-year-old black teenager Trayvon Martin in Florida.
"There are very few African American men in this country who haven't had the experience of being followed when they were shopping in a department store. That includes me," Barack Obama said last month. "Trayvon Martin could have been me 35 years ago."
Martin Luther King's dream is famous but in many aspects, a dream is what it remains.
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