The modern history of France is a peculiar business. The nation seems never to have quite survived the wounds of the French Revolution, and violent outside interventions seem to make this horribly clear.
The Prussian invasion in 1870 led directly to the slaughter of the Communards in Paris the following year. The Nazi invasion in 1940 seemed to lead, not so much to occupation - as it did in the rest of occupied Europe - but to a kind of civil war: 75,000 French Jews were deported, and there were French people at the heart of the efforts both to deport them and to defend them.
Now the recent attacks in Paris seem to have made divisions clear again - the same divisions that are here too, but somehow more urgently and more frighteningly.
I have been wondering about the French treatment of Muslims - banning the burka and niqab in public, and where The Front Nationale has taken power, banning halal meat from school lunches. Islam is an afront to French secularism in a way that it isn't to other nations which have no such ambition.
The controversy over the recent front page cartoon in Charlie Hebdo is part of the same problem. It is understandable, and yet still insensitive given that so many law-abiding French citizens would find it deeply offensive.
I can't help wondering whether this difficulty that France sometimes has of assimilating Islam has something to do with the difficulty France currently has with anti-semitism.
I've always argued that anti-semitism emerged out of a medieval horror of banking, but I'm not sure about the relevance of this to modern Europe. It may just be what happens when religious minorities start to feel the heat.