For a long time it was generally assumed, in the region and elsewhere, that peace was impossible, and that the Arabs' struggle against Israel would continue until they achieved their aim of destroying the Jewish state. Meanwhile, Israel could survive and even serve a useful purpose as the one licensed grievance in the various Arab dictatorships, providing a relatively harmless outlet for resentment and anger that might otherwise be directed inward. In this phase, the only peace that could be expected was the peace of the grave.

The more recent history of the Middle East shows a significant change and, notably, two possible paths toward peace. One of them is limited and therefore more feasible; the other is comprehensive and therefore remote and problematic.

One approach to peace is exemplified by the policies of Anwar Sadat, president of Egypt until his assassination in 1981. He sought peace and publicly declared his willingness even to go to Jerusalem. Sadat did not take these measures because he was suddenly persuaded of the merits of Zionism. His reason was more practical and immediate - his awareness, shared by a growing number of his compatriots, that Egypt was rapidly becoming a Soviet colony. Already the Soviet presence in Egypt was more widespread and more obtrusive than the British had been.

Sadat realized that, on the best estimate of Israel's power and the worst estimate of its intentions, Israel was far less a danger to Egypt than the Soviet Union was. He therefore decided on his epoch-making peace initiative.

Despite many difficulties, the 1979 peace accord signed by Egypt and Israel has endured ever since - at best cool, sometimes frosty, but preserved for the mutual advantage of both sides. In Iran, Sadat's murderer is venerated as a hero of Islam, and a street in Tehran is named after him.

In several Arab countries at the present time, and in wider Arab circles, there is a growing perception that once again they face a danger more deadly and menacing than Israel at its worst: the threat of militant, radical Shiite Islam, directed from Iran.

This is seen as a double threat. Iran, a non-Arab state with a long and ancient imperial tradition, seeks to extend its rule across the Arab lands toward the Mediterranean. And it is an attempt to arouse and empower the Shiite populations in Iraq, Saudi Arabia and the Gulf and other Arabian states, long subject to Sunni domination. Iranian tentacles are spreading westward into Iraq and beyond by the northern route into Syria and Lebanon and by the southern route to the Palestine territories, notably Gaza.

This double threat, of Iranian empire and Shiite revolution, is seen by many Arabs, and more particularly by their leaders, as constituting a greater threat than Israel could ever pose - a threat to their very societies, their very identity. And some Arab rulers are reacting the same way that Sadat did to the Soviet threat, by looking toward Israel for a possible accommodation.

During the war in Lebanon in 2006 between Israel and the Iranian-supported Shiite militia Hezbollah, the usual Arab support for the Arab side in a conflict was strikingly absent. It was clear that some Arab governments and Arab peoples were hoping for an Israeli victory, which did not materialize. Their disappointment was palpable.

We see similar ambiguities over the situation in Gaza.

On the one hand, pan-Arab loyalty demands support for Gaza, under whatever type of Arab rule, against the encroaching Israelis. On the other, many see the Gaza enclave - ruled by Hamas, a Sunni group but increasingly controlled by Iran - as a mortal threat to the Sunni Arab establishment all round.

In this situation, it is not impossible that some consensus will emerge, along the lines of Sadat's accommodation with Israel, for the maintenance of the status quo. Such a peace, like that between Egypt and Israel, would be at best cool, and always threatened by radical forces both inside and outside. But it would certainly be better than a state of war, and it could last a long time.

The second hope for change would be the growth of real democracy in the Arab world. Though unlikely at the present time, there are signs that such a development is not impossible.

Some Arabs have even been willing to speak out and welcome Israel as a pioneer of democracy in the region, a model that could help them to develop their own democratic institutions. Some have drawn attention to the fact that the at-times- disprivileged Arab minority in the state of Israel enjoys greater freedom of complaint and dissent than any group in any Arab country. A striking example is the current wave of protests among Israeli Arabs against the Israeli action in Gaza; open, outspoken - and unpunished. This does not go unnoticed.

The expression in Arab countries of any opinions favorable to Israel is unpopular, even dangerous, and sometimes fatal. The extent to which such opinions are held is therefore problematic, to say the least. But there are clear indications that they exist, and some have been willing to risk their lives in order to express them. If they increase and lead to acceptance and cooperation between the two sides, the Middle East might once again resume its place, which it enjoyed in both ancient and medieval times, as a major center of civilization.

In the past, any assessment of the prospects for peace in the region would have assigned a major, perhaps decisive, role to outside powers. This is not true today.

In earlier times one would have assigned a major role to Europe, but at the present day what matters is not so much the European role in the Middle East as the Middle Eastern role in Europe. A prominent Syrian intellectual recently remarked that the most important question about the future of Europe is: Will it be an Islamized Europe, or a Europeanized Islam?

The possibility remains that there will be no peace - in which case the most likely outcome for the region as a whole is a descent into chaos and mutual destruction, perhaps by that time involving an Islamized Europe, and leaving the future of the world to be shared or contested between Asia and America.

Bernard Lewis is professor emeritus of Near Eastern Studies at Princeton University.