The British statesman Lord Palmerston reckoned only three people had ever understood the Schleswig-Holstein question that caused several wars in the mid-19th century.
One was dead, one had gone mad and Palmerston himself had forgotten.
Syria is getting a bit like that. The great powers are involved - the United States and Western Europe on one side, Russia and China on the other. The bitter regional rivals Shiite Iran and Sunni Saudi Arabia are backing different sides, as are Islamist organisations Hezbollah and al Qaeda.
The conflict falls within 9/11's long shadow. Israel and the West fret that the regime's chemical weapons could fall into the hands of jihadists fighting for the rebels.
And, like Saddam Hussein before him, Bashar al-Assad insists the West should be thanking him rather than threatening him since the essentially secular regime he inherited from his father has plenty of runs on the board when it comes to ridding the world of Islamist militants.
How quickly they forget. Just a few years ago, the CIA was rendering particularly obdurate terrorist suspects to Syria in the hope that the regime's medieval approach to interrogation would bear fruit.
The enemy of my enemy is my friend is an age-old principle of geopolitical manoeuvring. It is nevertheless hard to believe that, having spent a dozen years trying to annihilate al-Qaeda, the US might end up fighting alongside it.
Given the complexity, it's not surprising that both the pro and anti-interventionists are struggling to nail the debate. While supporters of a punitive strike were put on the back foot by the House of Commons "no" vote, the case against is hardly watertight.
Legalists, led by United Nations Secretary General Ban Ki-moon, insist an armed attack not authorised by the UN would be illegal. Bearing in mind the process required to get to that point, this amounts to placing the international community in thrall to Russian President Vladimir Putin.
And if you're going by the book, what about the 1993 Chemical Weapons Convention? As Barack Obama pointed out, the international community drew a red line with this agreement by outlawing the production, stockpiling and use of such weapons.
The convention has been ratified by 189 of the 196 states recognised by the UN and signed by two others. The five hold-outs include pariah state North Korea, and Syria.
Ban says an attack will make a political settlement even more difficult. One is entitled to ask: what political settlement? The Assad clan has given every indication it would rather reduce Syria to rubble and scorched earth than participate in negotiations in which regime change is on the table.
He warns an attack might unleash further bloodshed and turmoil. With 100,000 dead and millions displaced, you could argue that doing something couldn't be any worse for the Syrian people than doing nothing.
When the American, British and French governments cited intelligence reports as proof that Assad's forces carried out a chemical attack, sceptics understandably evoked the "irrefutable evidence of weapons of mass destruction" provided by the same sources which became the pretext for invading Iraq.
The Iraq comparison can be overstated. There weren't any WMDs; there were hundreds of people poisoned in that Damascus suburb.
Then there's the suggestion that it doesn't make sense for the regime to have used chemical weapons: "It seems completely ridiculous that the regular armed forces, who are actually on the attack and in some places have the so-called rebels surrounded and are finishing them off, would use prohibited chemical weapons," argued Putin. "It doesn't fit into any logic."
Given how often human beings act in ways contrary to their own best interests, it's illogical to automatically ascribe logic. Perhaps the regime thought it would get away with it. After all, plenty of people think the regime should get away with it. It still might.
And if you're running the line that the rebels used chemical weapons on their supporters in a black propaganda operation aimed at prompting international intervention, you need to address the questions of how the rebels got their hands on these substances and what delivery system they used to inflict them.
Serbian tennis player Novak Djokovic drew on his experience of growing up during the Balkans conflict: "I'm totally against any kind of weapon, any kind of air strike, missile attack. I'm totally against anything that is destructive. I know it cannot bring any good to anybody."
Yet a lot of people caught up in that conflict, especially Bosnians and Kosovars, were grateful for Nato's bombing campaign. Without it, they probably would have been ethnically cleansed by some of his compatriots.