On Tuesday, the French national soccer team will play England in London. It promises to be the most symbolic friendly match since the English and the Germans held their impromptu kick-around in no man's land to celebrate Christmas, 1914.
There has been and will yet be a lot of brave talk about refusing to be intimidated. There almost certainly won't be an attack at Wembley on Tuesday, because the security personnel present will probably outnumber the fans.
But the takeaway from the failed assault on the Stade de France is that the big one is coming. As long as Islamic State or some group like it has the will to kill indiscriminately, no target is as inviting as a full arena.
Like any other public space, they are nearly impossible to fully protect. Unlike every other public space, they figure centrally in just about everyone's cultural imagination. Also, they are filled with camera crews. It's one place you can guarantee that your perverse variety of revolution will be televised.
It does not take any deep insight into the Western value system to understand that if we cannot be safe while at play, we will not feel safe at all.
On that basis, the slim details suggest how close Friday's violence in Paris was to being exponentially worse.
At least one of the militants came to the France-Germany game intending to detonate a suicide bomb in the stands. If reports are correct, he made several simple tactical errors.
He waited until the game had already been under way for 15 minutes – when he would be one of a few tardy entrants, rather than one amid thousands.
He chose an entrance close to the players' tunnel, where security would be heaviest. He acted in such a way that he drew the notice of a guard, who attempted to search him.
The attacker was chased off and killed only himself. A second attacker at the stadium also failed to gain access.
If either terrorist had made just a couple of different decisions – show up early rather than late; go to a more remote gate; keep your cool – this could've ended in unprecedented carnage. One suspects the next one to try it will learn from those mistakes.
We'll go on now. That's what we do these days. We latch onto a hashtag, hold a candlelight vigil and after a seemly period of virtual mourning, move on. While we can simulate involvement from this side of the ocean via obsessive consumption of breaking news and amateur video, we aren't actually invested in any of this. That's because we don't believe it can happen here. Even the Boston Marathon bombing feels like a long time ago.
They don't have that luxury in France. They're in a de facto war now. It's more likely to get worse before it gets better.
On Monday, French authorities will hold a previously planned meeting to discuss safety for the coming European Football Championships. Ten French cities will play host to the four-week tournament, beginning in June.
One can only imagine the level of dread with which the country's security services are approaching that happy occasion.
They can lock down the interior of the stadiums. They cannot insulate all of the spaces around them, or anywhere else fans gather en masse before and after a game.
It's too late to cancel. Doing so would send a terrible, capitulatory message in any case. When you talk about praying for France, this is a rather more useful sort of divine wish list. Pray they can pull this off.
French intelligence has already failed spectacularly twice this year. They must now be operating on the assumption that they don't know what's coming. They're depending on the observant security guards of the world to rescue them. The system doesn't always work that well.
At the opening match of Euro 2008 in Basel, Switzerland, someone sitting in front of us put a knapsack down in his seat and left.
Fifteen minutes into the game, a colleague and I were sitting there wondering what to do. Eventually, we called a steward. He poked the bag for a bit, shrugged and wandered off. No one ever came to get that bag. The guy I was with said, "Either he died in the bathroom or the detonator failed."
We laughed because we didn't really think it was possible. We would likely not make that mistake again.
The entire Euro – really, the lead-up to any major sports event in Europe for the next little while – will be spent on tenterhooks. Until France gets out of it safely, this will be the most emotionally fraught sporting event in modern history. Until the one that follows.
Eventually, something's going to happen. Then, we'll have to decide what to do next.
A few years ago, I polled a bunch of deep thinkers about what they thought might change in sport over the coming 50 years. Among other things, they saw a return of bloodsport and the end of the Olympics. Syd Mead – the visual designer behind Blade Runner – thought football would be played by cyborgs.
The suggestion I remember best was that the live experience of sport would end. There would be no more fans in stadiums. Fields and rinks would become soundstages.
This change would be prompted by "a precipitating event" – a 9/11-level catastrophe at an arena. After that, people would retreat in fear, insurance premiums would cripple stadium owners and TV would become the sole method of sports consumption.
It seemed conceivable at the time. It seems moreso with each passing year.
I still believe that the ritual aspects of sports viewership – that quasi-religious binding force – are too deep-rooted to abandon. As long as there is a hometown team to support, its believers will need to gather together.
But I also believe that our dedication to that simple pleasure will soon be sorely tested. Then we'll see if a vigil can ward off the resultant fear.
Cathal Kelly