Why is this image so powerful?

Even before the caption is read and the context explained, it has a very strong visual resonance.

Obama is obviously an historical figure, a phenomenal orator, a symbol of humanity and intellect. With his image comes a huge amount of that recollection and meaning: the victory speech after the Iowa primary in January 2008 (“They said this day would never come”), the victory speeches after the two elections (2012: “The role of citizens in our democracy does not end with your vote”), the basket ball, the humor of the correspondent’s diner, the battle with Donald Trump and so on.

The pose is somewhat humble and inquiring and Obama is alone, looking confident but curious.

But that is only the start of the meaning. That Obama is sitting on the bus where Rosa Parks once made her historic protest changes the picture altogether. Park’s refusal to give up her seat to a white passenger became a powerful weapon in the civil rights movement’s campaign which would eventually change laws and end segregation; her act is a landmark on the continuing struggle for racial equality in the US.

The bus is in a museum now, of course, and Rosa Parks herself died in 2005. But the act lives on a strong symbol. Fifty-two years and a few months after Park’s original ‘disobedience’ led to her arrest, Obama was sworn in as US president, the ultimate proof that – whatever racism remains in America – it is not ingrained in the institutions through which the country is run.

Race at times seems to be the least part of the Obama presidency. I’m sure that’s how it should be. However, this image reminds us that it is no small achievement for a country that – within living memory – built racism into its laws, to elect a president who might have been the victim of such segregation.