In 2008, Barack Obama wowed a euphoric 200,000-strong crowd in Berlin as the self-appointed embodiment of the power of politics to ignite change.
On Wednesday, after more than four tough years in power, he will stand up in Berlin again, as a testament to the difficulty of remoulding domestic and global political forces that combine to frustrate change.
In Berlin five years ago, candidate Obama defined eight foreign policy goals that would motivate his subsequent administration, arguing that the world faced a unique moment of "possibility."
Here is a mid-presidency report card on how well he has done.
"This is the moment when we must defeat terror and dry up the well of extremism that supports it..."
Obama killed Osama bin Laden and with a ruthless drone campaign wiped out much of Al-Qaeda's core leadership.
There have been no major September 11-style attacks on the US mainland in his tenure.
But Al-Qaeda has morphed into a brand adopted by smaller, but fast diversifying terror groups, bedding in where political insecurity festers.
The Boston bombings in April revealed a threat from home-brewed radicalism. Obama failed to honour his plan to close Guantanamo Bay, and civil liberties groups worry about his expansion of US drone and surveillance programmes.
"This is the moment when we must renew our resolve to rout the terrorists who threaten our security in Afghanistan..."
Obama will speak in Berlin the day after NATO handed the lead for operations in Afghanistan to local forces as it winds down combat operations by the end of next year.
After America's longest war, doubts remain over the capacity of Afghan forces and the corruption-tainted Kabul government to sustain themselves after NATO leaves and the Taliban remains.
"This is the moment when we must renew the goal of a world without nuclear weapons..."
Obama's talk about a nuclear-free world was always an aspiration rather than a realistic goal of his presidency.
But in one of his major foreign policy wins, Obama concluded a new Strategic Arms Reduction Treaty (START) with Russia in his first term, and is probing President Vladimir Putin's willingness to make new cuts.
Obama has presided over programmes safeguarding stocks of vulnerable nuclear and radiological material in the former Soviet Union and central Asia to keep them away from terrorists.
But nuclear drives by Iran and North Korea have powered ahead during Obama's administration, leaving him with a mixed non-proliferation legacy.
"This is the moment when every nation in Europe must have the chance to choose its own tomorrow free from the shadows of yesterday..."
Obama's comment was meant as backing for a strong European Union and better relations with Russia.
Europe has been mired in debt-inflicted troubles for Obama's entire tenure, but the president has often seemed more interested in booming Asia.
Still, he is throwing his weight behind a new effort to frame a huge new EU-US trade pact.
Obama was as good as his word and "reset" relations with Russia in his first term, but Putin's return reintroduced a chill and the two sides are estranged over Syria.
"This is the moment when we must build on the wealth that open markets have created, and share its benefits more equitably..."
Obama's performance on trade that is "free and fair for all" may depend on the eye of the beholder. And he is not alone to blame for the failure of global trade talks.
He stresses labour standards and environmental protection in talks for the new EU trade deal and a proposed Trans-Pacific Partnership (TPP) trade pact.
"This is the moment we must help answer the call for a new dawn in the Middle East..."
Obama's entire presidency was built on an impulse to extract the United States from costly wars in the Middle East.
He was not to know in 2008 that tectonic change would sweep the region in the Arab Spring, but has struggled to frame a coherent response. Obama's hopes of brokering Middle East foundered on the intransigence of Israelis and Palestinians.
He did pull US troops out of Iraq, but the country is teetering on the edge of a new violent abyss.
Syria's inferno may spill over its borders and destabilise the entire region and Obama may soon reach a point when he will face a decision about whether to attack Iran's nuclear programme.
While he cannot be blamed for the turmoil, historians must decide whether he was right to keep Washington on the sidelines or whether other policies could have stemmed the tide of unrest.
"This is the moment when we must come together to save this planet..."
Obama's effort to tackle global warming evaporated amid gridlocked US politics at a time when his nation was consumed by fear over economic collapse.
US efforts to fight climate change at a global level also petered out. Obama did agree this month with new Chinese president Xi Jinping to make a joint effort to tackle hydrofluorocarbons.
Obama has introduced new US standards on vehicle emissions and is rumoured to be readying new executive actions to get around the logjam in Congress.
"This is the moment when we must give hope to those left behind in a globalised world..."
Obama will get to this part of his foreign policy plan when he embarks on a trip to Africa next week.
While Washington remains a major foreign aid donor and has welcomed developing world leaders into global summits, it is tough to point to a single major US action that has helped Obama live up to this vow.