President Obama's overseas trip is not quite over, but some lessons from it are already clear. The main one is that the world remains an uncooperative place.
Mr. Obama can renew the long quest for a world without nuclear weapons, but North Korea will go ahead and test its missile anyway.
The president may urge Iran to turn away from its nuclear ambitions, but the regime in Tehran will respond by telling President Obama and the leaders of other nuclear powers to dismantle their own arsenals.
The president may outline a plan for Afghanistan that Europe likes, but that doesn't mean the Europeans will send combat troops to help.
There were many who believed that all this would be different when the dashing new American president took office. For one thing, this president would listen to the views of European leaders, not dismiss them. And the Islamic world, it was thought, would be assuaged by the new President's Muslim-sounding name.
That may have helped in Turkey, already a U.S. ally, but so far not in Iran. And North Korea, well, it is what it is, and has long been, an international menace and nuclear blackmailer. It seems that our president may be something completely different, but he confronts a world that is not.
In the end, Mr. Obama may succeed in the world. And it may help that he is not George W. Bush and it may help that he is Barack Hussein Obama. But the early evidence is that it won't help much.