President George W. Bush embarks this week on a trip to the Middle East that may determine how history judges his legacy. So far, it is safe to say that the judgment will be largely negative. Mr Bush’s foreign policy has undermined America’s global legitimacy, not to mention his own credibility. He has plunged the US into a protracted conflict in the Gulf region while neglecting the increasingly ominous al-Qaeda challenges in Afghanistan and Pakistan. Last, global public opinion has turned against the US.

But a great deal could change if Mr Bush could make happen what he has just predicted in an interview with an Israeli newspaper: “There will be a comprehensive peace signed by the end of this year” between the Israelis and the Palestinians. Indeed, such a peace would be a breakthrough of genuinely historic dimensions.