The second is that he has not chosen the real seat of modern Islam, which is to be found in the country in which Obama grew up -- Indonesia, by far the world's most populous Islamic nation. With Pakistan and Bangladesh and the 150 million Muslims of India, there are more than twice as many Muslims in Asia than there are in the Arab world.
Indeed, Arab Muslims may already be outnumbered by the Muslims of sub-Saharan Africa, which on current demographic trends is likely to contain a majority of the world's Christians and Muslims by the year 2050. Obama knows this tradition of Islam in Africa. His father, as a Muslim from Kenya in East Africa, was a part of it.
The next oddity is that Egypt is no longer the undisputed center of the Arab world, as it was in the days of President Nasser in the 1950s and 1960s and of President Sadat in the 1970s. The oil wealth and economic dynamism of the Gulf, and the relatively low-key diplomatic role that Egypt has played since it signed a peace treaty with Israel, have undermined Egypt's long pre-eminence. In that sense, Obama's visit is a political gift for the Egyptian government.
"It sustains and consolidates Egypt's position in Middle East politics, being recognized by a superpower as the center of the Muslim world," said Gamal Abdel Gawad, head of the international relations unit at Cairo's Al-Ahram Center for Strategic and Political Studies. "This is definitely a plus for Egypt and for the Egyptian government."
And finally, Egypt is a very problematic venue for a speech such as this, since it invites comparison with the important speech made in Cairo four years ago by Secretary of State Condoleezza Rice, in which she noted that "for 60 years, the United States pursued stability at the expense of democracy in the Middle East -- and we achieved neither."
Egypt was a critical point for the ambitious policy of the Bush administration to steer the Arab world and Islam toward democracy and a greater regard for human rights. That policy, for all its good intentions, failed. Egypt's President Hosni Mubarak, formerly an air force general, clamped down on the opposition party, jailed its leader Ayman Noor for three years on trumped-up charges and maintained his authoritarian rule.
So Obama faces a political challenge in Cairo, and not simply a cultural-religious opportunity. If he downplays human rights in Egypt, then for many of America's natural allies and supporters in the region the result will be disappointment and disillusion. If he merely spouts rhetoric on human rights with no follow-through on tough regimes, the disillusion will be extreme. If he follows through (as Bush did not) and turns rhetoric into hard and serious policy, he will undermine those regimes like Egypt and Saudi Arabia on which he must rely for diplomatic progress in the Middle East as a whole.
And we have already heard the rhetoric, delivered in Obama's inauguration speech in January, when he said: "To those who cling to power through corruption and deceit and the silencing of dissent, know that you are on the wrong side of history, but that we will extend a hand if you are willing to unclench your fist."
Last week a group of young Egyptian human rights activists visited Hillary Clinton at the State Department, and she introduced them with the following words: "I think that there is a great awareness on the part of the Egyptian government that with young people like this and with enhanced communications, it is in Egypt's interest to move more toward democracy and to exhibit more respect for human rights."
But beyond all these issues, the dominant question for the region will be hard policy on the implacable Israeli-Palestinian conundrum. Al-Ahram's Gamal Abdel Gawad, who reflects official Cairo thinking, noted, "It's about the U.S. being careful to develop an independent position and policies vis-a-vis the Arab-Israeli conflict. What Arab countries are looking for is that the U.S. is more independent and tries to stand more or less at an equal distance from both sides in the region."
Mubarak's Islamic opposition is even tougher. Obama's trip will be "useless unless it is preceded by real change in the policies of the U.S. administration toward the Arab and Islamic world," Mohammed Habib, deputy director of the Muslim Brotherhood, said in a comment on the group's Web site. "The U.S. administration is attempting to recruit all the Arab states to implement its permanent agenda that favors the Zionist entity."
We have yet to see just how far Obama is prepared to go to promote the two-state solution he supports, how much he will recast the U.S. position in the Middle East, and how tough he will get with Israel on settlements and U.S. financial aid. That really means how much political capital he is prepared to spend on facing down the powerful pro-Israel lobby in Congress.
There is little doubt that he will deliver a fine and powerful speech in Cairo. But the exalted expectations aroused by his ancestry and background -- and by his rhetoric -- have to be reconciled with the hard realities of American interests, of Israeli power, of Palestinian divisions and of jihadist intransigence. Speeches are one thing. Policy is another.