For decades after World War II, Italy seemed to get nowhere, because no sooner was a government in power than it had collapsed in disarray. The desperate state of many things in Italy is a legacy of those revolving door governments — whether it is ramshackle infrastructure or the power of mafias in health, education, football or any other field you care to think of.

The ostensible culprit for Romano Prodi’s pratfall last week, jumped on hard by the mainstream Italian media, was the far left component of the coalition who was against Italy fighting alongside the Americans in Afghanistan and giving the US the go-ahead to build a new base in the city of Vicenza.

Yet as the days passed, everybody woke up to the fact that the Trotskyite and the pacifist were not actually the ones to blame. Three senators for life, including Giulio Andreotti, a powerful Christian Democrat politician for more than 40 years, now aged 87, had been expected to vote for the government but instead one voted against and two abstained. These were the votes that sank the government.

The suspicion quickly arose that Andreotti and the others had voted as they did, not because they were opposed to Italy’s philo-American foreign policy (which they ardently support), but to bring down the government: The reason being that Prodi had insisted, despite strenuous opposition from the Catholic Church, on bringing in a law to legalize civil unions.

And it was the Catholics who emerged from this week’s chaos in triumph, because to secure extra support Prodi has been obliged to dump the civil unions law. Cohabiting Italians, gay or otherwise, will continue to have no rights, unlike their counterparts in most parts of the EU. Poland is the other exception.

This little piece of modern Machiavelliana exposes the true reason for the chronic weakness of Italian governments. Italy is not one state but two: The unified Italian state, created in 1870; and the papacy coiled in the heart of the capital, the ultimate legatee of the original Roman Empire, which surrendered temporal power over the papal states but has never relaxed its grip on Italians’ hearts and minds.

Imagine that Hitler did not die in his bunker in 1945 but instead cut a deal with the new West German government, giving him continued sovereignty over a small patch of Berlin — and continued intellectual hegemony over the millions he had brainwashed during the previous decade.

How could a new German dispensation function with this incubus at the heart of the state, second-guessing its every move, checking and trumping every effort to dismantle its ideology?

Italy’s Vatican problem is a lot like that, with the difference that the church has been wielding its mind-control for nearly two millennia. The Treaty of Westphalia of 1648 that ended the Thirty Years’ War gave birth to the concept of the sovereignty of the nation-state, with states independent both from the Holy Roman Emperor and from the Catholic Church. Thanks to this treaty, sovereignty as the underlying principle in the formation of nation-states spread across the planet. But because Italy was host to the pope, it never attained real sovereignty. Mussolini achieved an uneasy cohabitation with the church, but after the war the Vatican was back in power through the Democristiani, who provided all Italy’s postwar prime ministers until 1981.