In strict military terms the daring advance of the Syrian rebels into Damascus looks like a case of overstretch. There has been nothing to suggest that the Free Syrian Army has recently received enough weapons or defectors to enable it to take control of the capital. Military logic suggests that they will, in due course, be pushed out by superior forces, with many casualties.
But military logic is not driving this conflict. Syria is not a country of institutions but one of networks, of family, clan and religious confession. The bomb that blew up a meeting of the regime's top security chiefs on Wednesday has done more than deprive it of its defence minister, and the brother-in-law of President Bashar Al Assad, Assef Shawkat.
It has raised a whole series of questions in the minds of the inner circle: "Who can we trust, if a bomb - according to a still rather sketchy official version of events - can be brought into the most securely defended room in the whole country?" As for the regime's allies in the wider population - the merchant aristocracy of Damascus and Aleppo, the Christians and other minorities - they must be asking themselves, "If the president cannot defend Damascus, what purpose does he serve?"
As for the western powers, they have been jolted off the diplomatic merry-go-round by the realisation that the Free Syrian Army, while it may not win the battle of Damascus, is pressing events to a faster denouement than they expected.
The western powers look even more impotent than in the past. Their game plan was, over the coming weeks, to bring the Russians around to accepting that the Assad clan had to go, and to secure some kind of "managed transition" to Mr X (or General X) who would take control of the country, restore peace and hold elections.
But the box marked "Syrian national saviour" has remained stubbornly unfilled.
In the US, the White House is still talking of "transition" but this word looks ever more hollow. The lesson of the removal of Arab dictators in Iraq, Libya and Yemen is that once the big man has gone, there is nothing but a vacuum to transition to.
In Egypt, where the army is a national institution, Washington was able to find a solid military partner to take over, and in Tunisia, the most Europeanised of the North African countries, the exiled Ennahda party was there to replace the toppled dictator.
But Syria is far more like Iraq than Egypt or Tunisia. The whole Syrian power structure had been hollow for years, with no one but careerists believing in the Baath party and the population acquiescing out of fear of the security police or anxiety that something worse - like the Iraqi model - would follow the end of the Assad era.
Much of the population has lost its fear of the secret police, and the fighting in Damascus shows that the anxiety is being overtaken by events. Without any person or institution to take over, it is hard to imagine any outcome other than spreading civil war and increased foreign intervention - in the form of aid to the rebels from their supporters abroad and rising numbers of foreign jihadis piling in.
Predictions are unreliable when the situation on the ground is murky, but it is clear that the Holy Month of Ramadan, far from providing a respite for the regime, will be a time of great danger. With large crowds going to the mosque late at night, the authorities will face an insuperable problem of crowd control. It would be a desperate army commander who turned his guns on worshippers emerging from a place of prayer. And even if the shots were fired by the shabbiha, the regime's Alawite militia, no one would see any difference.
The Russians, the main backers of the Assad regime, are still insisting that the western powers and the Arab allies of the opposition have no magic bullet to remove the president from power. As the foreign minister, Sergei Lavrov, put it, "Assad will not go on his own and our western partners don't know what to do about that."
But it is quite likely that control of parts of the country will ebb away from the president, while being preserved in others, such as the heartland of the Alawite sect, the mountains of north-west Syria, where the French mandate authorities created an "Alawite state" in the 1920s and 30s. The logic of this would be an ingathering of the Alawites to their mountain fastness, after 40 years of power at the head of the state. Would Mr Assad return to the town of Qardaha, birthplace of his father, the former president Hafez Al Assad, and turn it into the Alamo of the Alawites? This option is much talked about, but for the moment it looks more romantic than realistic.
Thanks to the clarity brought to events by the Damascus bombing, we can see that the Americans have one clear interest in Syria - its chemical weapons arsenal. Washington does not want to see this fall into the hands of the Al Qaeda-linked elements in the opposition. Leaving aside the question of how significant these elements may be, it is fair to say that the Russians also do not want these weapons, including sarin and mustard gas, falling into the hands of the opposition and, in their nightmares, ending up in the hands of Chechen militants on their southern border.
This could be the basis of a deal between Washington and Moscow: safe passage abroad for the Assad family as part of a deal that would leave the chemical weapons under secure central control.
Would it work? All that can be said is that such a deal would be based on the real interests of the two countries, not on current wishful thinking, where the Russians are trying to hold back history and the Americans are pretending to rule the world, without daring to risk a drop of blood.
On Twitter: @aphilps