It's now a cinematic cliché. You know the scene: high-society types are quaffing champagne or dancing the foxtrot, while outside a revolution is brewing. Those on the inside remain in a cosy bubble of complacency, unaware of the storm about to hit them.
Well, the We Believe in Israel event on Sunday was not entirely like that. Rather than Dom Perignon, they were drinking tea and coffee with kosher-stamped milk and no one was dancing the foxtrot. And, viewed one way, the mood was the very opposite of complacency: fear of Israel's "delegitimisation" was a constant refrain.
Yet, self-congratulation was also the spirit of much of the day (full disclosure: a memorial service prevented me staying for the whole thing). There was loud applause as speaker after speaker praised Israel's wonderful hospitals, its start-up ingenuity, its "most moral army in the world." What the 1,000-plus delegates wanted to hear is that Israel is marvellous, terrific and fab - and that it is only malice or worse that prevents the rest of the world from seeing it.
I understand this need. When there is so much criticism of the world's only Jewish country, I understand why the community needs to immerse itself in a warm bath of affirmation, shutting out any thoughts that might spoil the mood - even if, for some, that meant booing Liam Fox, a hardcore Israel supporter, for daring to say that settlements are an obstacle to peace.
But it can also look a lot like self-delusion. For, by a quirk of timing, it just so happened that there was, in fact, a storm brewing outside.
While the delegates sat in sessions named, "Do they really hate us?", the IDF was opening fire on stone-throwing Palestinian protestors marking "Naqba Day" on Israel's frontiers with Syria and Lebanon. Instantly, Israeli politicians were warning of a third intifada, one that might include Palestinians to the north, south and east of the country as well as inside it.
And this storm is unlikely to blow over after a single day. For what is now clear is that the Arab Spring will not leave the Palestinians untouched. Despite feeble efforts to pretend that the Syrian authorities were behind Sunday's events, seeking to create a diversion, there is good evidence that the action had been planned by online activists for several months.
Worse, when Israel says that demonstrations are the work of shadowy foreign agitators, its spokesmen sound just like the dinosaur Arab regimes in the region, the Libyas and Yemens, who say the exact same thing about the protests in their countries.
This is the larger danger here: that Israel is placing itself on the wrong side of a popular movement spreading across the region, standing opposed to those marching for long-demanded rights. It is said that the Assad regime has one loud advocate in Washington, arguing that the west should go easy on the brutal Syrian dictatorship for fear of the alternative - and that advocate is Israel.
So, yes, we should laugh at the hypocrisy of Damascus condemning Israel ("How dare you open fire on unarmed Syrian citizens: that's our job!"). But we also need to consider what it means if the next target of a movement, seen across the world as essentially non-violent and thirsting for democratic rights, is not this or that Arab government but Israel. (It won't wash to say that, for example, the protesters from Syria were crossing Israel's sovereign borders: they crossed into the Golan Heights, recognised by no one as Israeli territory.)
Meanwhile, another storm is coming. In September, the UN General Assembly is set to recognise Palestine as a state on the 1967 borders. The US does not want that outcome, but is very reluctant to block it. The result is that Israel's presence in the West Bank will be seen as akin to Iraq's presence in Kuwait in 1990: as the occupation of a UN member state. If you think Israel's case is already hard to make, it's about to get a whole lot harder.
The only solution to these twin challenges is for Israel to get out in front, to offer its own plausible peace initiative - one that might head off both the incipient Palestinian Arab Spring and unilateral statehood. Whooping and cheering in the name of solidarity might make British Jews feel good, but Israel needs something so much more serious.