A?s I was leaving Cairo after Hosni Mubarak stepped down, I asked Esraa, a young woman who was one of the leaders of the revolution: “What was your objective?” She said, “taghier al nezam”, a change of the system. The Egyptians brought down the head of the system, but not the system itself. That is the challenge now.

Egypt’s revolution, like Tunisia’s, represents a model for change in the Middle East. These societies are not fragmented by tribal or sectarian conflicts. Despite differences of faith or even the occasional collisions between them, Egypt is united. In contrast, the second model for revolutions is that of Yemen, Libya and others in the making. In these cases, unfortunately, tribal and sectarian conflicts may lead to chaos and civil war, ultimately dragging the Middle East backward into conflict and fanaticism, not forward.

To avert this, the revolutions in Egypt and Tunisia cannot be allowed to fail. Egypt is the key. With 85m people, it is the largest country in the region and the heart of the Arab world. Making sure it succeeds is essential for the spread of democracy and stability of the world’s energy supply as well as for peace in the region. What can be done?