CAIRO — The fighting began in mid-afternoon on Talaat Harb Street, close to Tahrir Square. I watched as young men, their faces bloodied, were rushed away. The crowd eddied back and forth beneath volleys of stones and rocks. Young men heaved sacks of rubble, never in short supply in Cairo, toward the front. Cheers erupted when the protesters advanced only to die away in headlong retreat.

There was no trace of the Egyptian state — not the police, not the military — as liberal and socialist opponents of President Mohamed Morsi and his Muslim Brotherhood backers battled over several hours in the bloodiest clash between the nation’s secular and Islamist currents since the revolution that ousted Hosni Mubarak 20 months ago. More than 100 people were injured.

The demonstrators on Talaat Harb, their passage into the iconic square blocked by a phalanx of stone-throwing Brotherhood supporters, were incensed. They had long planned this demonstration in anger at Morsi’s first 100 days as president and in protest at what they see as a flawed, over-hasty procedure for drafting a new constitution. Now the dominant Brotherhood had hijacked proceedings.

“We called this protest three weeks ago to dissolve the constitutional assembly, and they decided yesterday to come to the square and confront us,” Karima el Hefnawy, a prominent socialist activist, told me. She was pale and shaking with rage. “The Brotherhood does not work for the people but its own interests. Now the Egyptian people can see their fanaticism.”
George Ishaq, a leading liberal, had a lapidary verdict: “This is a black day in the history of the Muslim Brotherhood.”

I had stood among the jubilant crowd in Tahrir Square in February, 2011, as the very forces hurling rocks at each other last Friday — the Brotherhood and the young more secular Egyptians who ignited the uprising — embraced and celebrated the toppling of Egypt’s 30-year dictatorship.

So has that glorious dream of liberty, democracy and the rule of law crumbled, as most things do, into the enveloping Cairo dust?
Revolutions give way to their aftermaths. Unity cedes to disunity as binding adrenalin fades. A shared enemy is supplanted by competing interests. The groceries must still be bought. Egypt is no exception to an old rule. I spoke to several disappointed friends in the liberal camp who now say they favor enlightened despotism.

These liberals are too bitter too soon. They are too dismissive of the road traveled these past 20 months through more than a half-dozen national votes and a bitter confrontation between the military and civilians — events that might have upended Egypt but have seen civilians prevail, U.S.-trained generals salute an Islamic president, and a tenuous stability hold.

But do the enduring troubles in the largest Arab state betoken looming collapse or the inevitable churn of liberty being birthed? And can Morsi, emerging from the conservative Brotherhood wing and elected with 51.7 percent of the vote, convince the 48.3 percent that they, too, have a place in the new Egypt?

These questions in turn pose another to the United States and the West: Should they pour much-needed funds and support into Morsi’s historic experiment in reconciling Islam and an open society, or conclude that any such attempt is stillborn and side again with some secular despot, uniformed or not?

The events Friday were troubling. The Brotherhood has a hard time accepting dissent. Its avowed reason for occupying Tahrir — the acquittal last week of Mubarak-era officials accused of involvement in the deadly camel charge on protesters in the square last year — looked like righteous camouflage for suppressing an anti-Morsi demonstration. Islamists cannot rule and form the opposition at once.

Morsi has made mistakes. He fired the chief prosecutor last week over that camel-case acquittal and attempted to dispatch him as Vatican ambassador. Then — yes, Mr. President, the judiciary is independent — he had to reinstate him.

He made ridiculous claims this month in a big speech to a Brotherhood-dominated crowd: “We have achieved 70 percent progress in national security, 60 percent in the traffic, 40 percent in the garbage, 80 percent in bread and 85 percent with gas.”

Many Egyptians, stuck for hours in the 40 percent of traffic officially remaining, mired in the 60 percent of garbage outstanding, and struck by the 30-percent absent police, laughed. (Egyptians have a gift for laughter, one cause for optimism.)
Morsi is given to long perorations heavy on Koranic quotations. But he also has shown a deft hand in outflanking the military, courage in standing up in Tehran and denouncing Assad’s murderous Syrian regime, and — to the Western officials who deal with him — a strong sense of the need for inclusiveness. That instinct faces its most decisive test in the critical debate over a new constitution.

Freedom is not the subordinate clause some Egyptian liberals now turn it into. Democracy is precious precisely because it is fragile and unpredictable. The West — after Algeria and Gaza and decades of the hypocrisy that condoned the likes of Assad — must back Morsi to be better than Friday’s violence suggested.
On the constitution he must prove he is — or the Tahrir battle will presage worse.