When Hosni Mubarak and his sons appeared in the iron-barred cage of a Cairo court on Wednesday, the ink was barely dry on newspaper predictions that the trial would never happen. It was said that the generals who are the interim rulers of the country would not let it go ahead. The ex-president would be declared too ill to stand trial, or another pretext would be found for adjourning.
But these predictions were wrong, and shocking images of the 30-year ruler of Egypt behind bars were beamed around the world. Whatever happens in the future, those symbolic images can never be erased from the memory of Arab people. The message has gone out that no leader, however well protected by police and the military, is above the law. This is what the Egyptian revolutionaries wanted to see, and they have seen it.
There is likely to be a perverse reaction. No Arab leader will now leave office as readily as Mr Mubarak did, for fear of judicial retribution. The example of Egypt's King Farouk, who sailed into gluttonous exile after the Free Officers overthrew him in 1952, is consigned to the past.
The trial has aroused mixed emotions. Amid the jubilation at the start of the trial, there are many in Egypt who think it shameful that an 83-year-old man who is ill, but apparently not as ill as his lawyer has suggested, is put on trial for his life.
It is not for foreigners to tell the Egyptians how to run their country. They have to feel their way forward in these most difficult circumstances. But it is useful to point out some historical comparisons.
The current trial is not convened by revolutionary decree or put together by some Committee of Public Safety baying for vengeance. It is taking place under existing laws, which is to be welcomed. The judges and the prosecutor were all appointed to their posts under the old regime. Even the barred cage for the defendants - so shocking to viewers used to jury trials - is a routine part of the judicial system, applied in the trials of the thousands of Mr Mubarak's opponents.
This is a good sign for Egyptian justice, but also a severe test. It could hardly be more different from the fate of Saddam Hussein in Iraq. His trial looked like a puppet show, with the strings pulled by the unseen hands of the Americans. His execution - hasty and botched - now appears to have been more like an act of sectarian vengeance than blind justice.
That said, there are doubts as to whether justice, as demanded by the Egyptian revolutionaries and the relatives of the 850 people whose deaths Mr Mubarak is accused of ordering, will be carried out. Proving that a serving head of state ordered any killings is notoriously difficult. The five-year genocide trial of the former Serbian leader, Slobodan Milosevic, failed to reach a verdict before Milosevic died of a heart attack in 2006.
A prosecution dossier to back up the charges against Mr Mubarak - killing protesters, profiteering by abuse of power and selling gas to Israel at below market rates - could take a couple of years to assemble. Clearly Wednesday's opening was scheduled not because the prosecution was ready, but for political reasons. The Supreme Council of the Armed Forces needed to throw a sop to the revolutionaries.
There is also the ever-present danger of the trial descending into farce. It was a good decision to move it to a secure location, inside a police academy, to avoid any possibility of the court being stormed by angry protesters.
On Wednesday we had the spectacle of a mob of grandstanding lawyers vying for the microphone, to the clear annoyance of the presiding judge, Ahmed Refaat. Attention -seeking lawyers are not a uniquely Egyptian phenomenon, but ways have to be found to limit the crush.
The Mubarak defence wants to overload the trial with 1,600 witnesses, and subpoena the de facto, but almost invisible, ruler of Egypt, Field Marshal Hussein Tantawi. Egypt has a long legal tradition and it is not beyond the wit of the judges to cope with these problems.
But there are more serious issues. The court is orphaned: it does not have the strong support of the ruling generals, and there is no newly elected parliament or government to provide political backing. This is a political trial, but without a political foundation. This puts a terrible responsibility on the judges, who may find themselves isolated when they have to take difficult decisions.
The desire for vengeance is only too human. At the execution of King Louis XVI in 1793, the French revolutionaries rushed to dip their hands in blood as it spurted from his guillotined neck. The result was two decades of war in Europe. The hanging of Saddam Hussein did not hasten stability in Iraq.
The most important task is to balance the demands of justice with the need for reconciliation. Achieving the right balance would set a standard that the rest of the Arab world could copy.
For the families of the protesters Mr Mubarak is accused of having killed, the prospect of justice appear slim. He may not live long enough for a verdict. The only consolation will be that some truths about the way the Mubarak era was run will emerge. An unaccustomed light will shine on the murky figures in the background, particularly the senior officers in charge of security and the cronies who reaped the benefits of the privatisation of state assets.
The death of hundreds of people is a shocking statistic. But in a country of more than 80 million, Mr Mubarak's great fault was strategic. He put Egypt to sleep for 30 years, crushing its energies with a police state; he deprived young people of a future; and he robbed his country of its leadership in the Arab world, thus erasing a force for progress and innovation and allowing jihadism to take hold of some young minds.
Even worse, he ruled without making provision for a successor, as if his own fate and that of Egypt were inseparable. If this trial shows that no leader is above the law and no president should claim pharaoh-like immortality, it will have served its purpose.