Something ugly has been happening in Egypt this week -- and it threatens to tip the Arab world's most important nation into renewed turmoil.
The scenes have been reminiscent of the street protests at the height of the anti-Mubarak uprising nearly two years ago. Once again, the chants have been ringing out across Egypt's towns and cities: "The people want the regime to fall."
But there is a difference. No one believed that Hosni Mubarak was the legitimately elected head of state, chosen by the people in free and fair elections. Mohammed Morsi, on the other hand, can claim to be exactly such a leader, even if the elections that he won last May were far from uncontentious.
Morsi won 51.7 per cent of the vote in the second round run-off, against 48.3 per cent for his main rival, Ahmed Shafik. It is perhaps too easy to forget now just how close that result was -- and how deeply disappointed the many non-Islamist Egyptian voters were.
Revolutions rarely happen neatly, or in a straight line. The revolutions in eastern and central Europe in 1989, which saw successive Communist regimes toppled one after the other, were a rare exception, and they probably gave us a misleading impression of how simple it could be to sweep away decades of authoritarian rule.
In Egypt, President Morsi's opponents believe that he, together with the Muslim Brotherhood which they deeply distrust, has made an audacious power grab, by decreeing that -- even if only temporarily -- presidential decisions will no longer be susceptible to legal challenge.
Moreover, the Brotherhood have rushed through a new draft constitution, which is meant to be approved in a referendum in just eight days' time. This isn't the careful, methodical building of a new political system which many of the revolutionaries had in mind during those heady days of early 2011 -- instead, it looks to them like a bare-faced attempt by the Muslim Brotherhood to grab hold of the power they won in the elections, and make sure they'll be able to hang on to it for ever.
The counter-argument is that the courts are still stuffed with Mubarak-era judges, determined to prevent the country's new political leaders from effecting the changes that they believe the revolution legitimised.
Egypt is split in a multitude of ways -- by class, by religion, by education and by wealth. No one political group, and certainly not the Muslim Brotherhood which has emerged as the country's overwhelmingly dominant post-Mubarak force, can claim to represent the interests of more than one section of Egypt's voters.
The accusation being levelled at President Morsi is that he still thinks, and acts, like a Muslim Brotherhood leader, not like a national leader. He may say the right things -- but his opponents say his actions tell a different story.
And remember, as I have pointed out before, why the fate of Egypt matters so much. Its population, at 81 million, is greater than the combined total populations of all the other Arab Spring nations -- Tunisia, Libya, Syria and Yemen.
It has a history stretching back more than five millennia to the pharoahs. Al-Azhar mosque in Cairo has long been regarded as the seat of Sunni Muslim orthodoxy. And every head of the Arab League since its inception in 1945, with one brief exception, has been an Egyptian.
Just last month, Egypt was again instrumental in mediating a ceasefire between Israel and the Palestinian movement Hamas in the Gaza Strip. And with Syria in flames, no one in the Middle East wants to see Egypt slip into chaos, or worse.
So the challenge facing President Morsi is a daunting one. Judging by his TV address last night, he is in no mood to offer concessions to the protesters gathered in the streets. They, similarly, are in no mood to let him get away with what they insist is behaviour quite out of keeping with the aims of the anti-Mubarak uprising.
The stakes could hardly be higher.
Next week will be my last at The World Tonight after 23 years; my final programme will be on Thursday. That means that next week's newsletter will be my last in its current format, although it will continue in a somewhat different guise, and I will continue to write independently in the New Year. Full details will be in next week's newsletter.