The only meeting between the first black presidents of the U.S. and South Africa lasted only a few minutes and almost didn’t happen.

In May 2005, Barack Obama, a new U.S. senator, was riding to a Washington event when his office called. Nelson Mandela, whose decades-long fight against apartheid and efforts at racial reconciliation had inspired Obama to become engaged in politics, was in town and asking to see him. Obama seized the chance.

In Mandela’s room at the Four Seasons hotel, the man who had transformed South Africa rested in an armchair, legs up, a cane at his side. Obama bent to gently grasp Mandela’s hand. In an unpublished photograph taken by Obama aide David Katz, Obama is in silhouette while Mandela is bathed in light.

When Obama, 51, makes his first presidential trip to South Africa this week as part of a three-country visit to the continent, it will be too late for the sort of reunion with the 94-year-old ailing African icon that he may have once imagined, if any contact between them is even possible.

Still, Obama’s visit is inviting comparisons of these two presidents who each broke the colour barrier in different ways.

Mandela and Obama are both historic figures, Nobel Peace Prize winners, who leaped from being parochial politicians to symbolic forces of global change, helping to shed shameful aspects of their nations’ pasts.

Yet the comparisons only go so far. While Obama admires Mandela’s strength and resilience, he’s not seeking to be the standard bearer of the South African’s legacy, top aides say.

“I have never once heard President Obama in any way compare himself to President Mandela,” said Valerie Jarrett, a senior Obama adviser. “I know he feels that any challenges he may have simply pale in comparison to what Mandela endured.”

Some of Obama’s policies would probably have drawn criticism from Mandela, as did those of his predecessors, Presidents George W. Bush — Mandela called the U.S. “a threat to world peace” during Bush’s presidency—and Bill Clinton, for U.S. policies aimed at isolating Cuba, Iran and Libya.

Obama’s campaign calls for bipartisanship, racial unity and multilateralism “would have resonated with President Mandela,” said Jennifer Cooke, director of the Africa Program at the Center for Strategic and International Studies in Washington.

The president’s robust defense of anti-terrorism policies, such as expanding lethal drone strikes abroad and classified surveillance of telephone and Internet communications, likely would not, she said. “I think Mandela would find that anathema to broad ideals of principled foreign policy.”

The Reverend Jesse Jackson, the civil rights activist and a longtime friend of Mandela, agreed. While Mandela has held Obama in “high esteem,” he would be “troubled by” the U.S. drone policy, Jackson said.