The Pursuit of Italy, By David Gilmour

From outer space Italy looks more like a country than any of its neighbours, but Metternich's jibe that it was purely "a geographical expression" has infuriated Italian nationalists for generations. The reason is that Metternich was right. In this well-researched and engaging canter through the peninsula's history, David Gilmour claims that only two Italians between ancient times and the 19th century entertained the idea that Italy was, or might be, or ought to be a unified country: Virgil, the myth-making epic poet, and Machiavelli, some 14 centuries later.

Italy's attempt to celebrate the 150th anniversary of unification, which got under way last month, has provided plenty of ammunition for those who regard the Italian state as an abomination. Berlusconi's coalition government is dominated by the Northern League, which openly scorns the republic and has at times campaigned for the north to secede. The plans for the celebrations were marred by a massive corruption scandal. Instead of a surge of patriotic enthusiasm, the anniversary prompted a film entitled Noi Credevamo (We Believed), which depicts unification not as a liberation but as a disguised colonisation, leading to the permanent stunting of the south.

Now comes this book by Gilmour, whose previous work on Italy was a study of the classic Sicilian novelist Giuseppe di Lampedusa: another voice, this one well-mannered and unmistakably British, in the swelling chorus of hostility to Italian unification.

So if Italy was not a state, what was it? As Gilmour explains, there was not one Italy but a bewildering variety of alternative ones: the Italy dominated by ancient Rome, the Italy of the barbarian invasions, of the papal states, of the see-sawing wars between the popes' allies and those of the so-called Holy Roman Empire, and many others. In the absence of any sort of enduring unity or centralisation – especially after the fall of Rome – Italy's special genius proved to be the creation of city states: the descendants of the earliest communes in the peninsula, founded by the ancient Greeks.

There is thus a powerful family bond linking Periclean Athens, with all the qualities of culture and democracy which it created and enshrined, and the medieval Italian comuni of Florence, Siena,Venice and the rest. Gilmour is careful to avoid idealising these statelets. All of them had faults: they were beset by factionalism, that Italian speciality, and their chronic insecurity put them permanently at loggerheads with their neighbours, whom they generally despised.

The great Florentine writer Boccaccio, Gilmour tells us, believed that "the Sienese are credulous and the Venetians untrustworthy, Pisan women are ugly and Perugian men are sodomites, in the Marches the males are uncouth and mean-hearted." Sicily produces assassins, Naples thieves and grave-robbers, but worst are the "rapacious and money-grubbing" Genoese. "The only consistently good people," Gilmour summarises Boccaccio, "live in Florence, where the women are all beautiful and the men are noble, chivalrous, agreeable and wise."

Local chauvinism bred a tendency to bellicosity in many states, despite their often farcical (if endearing) ineptitude in the arts of war. Their small size made long-term survival problematic. Yet, as every tourist knows, these were wonderful creations which enshrined a vision of civilisation we can still relish today. Gilmour finds the same qualities persisting in jewel-like northern cities such as Crema and Cremona.

For Gilmour, the star of them all was Venice, governed with ingenuity and maturity by a ruling class that never got above itself. In his rather cosy depiction it is an England in miniature: maritime, sensible and tolerant, wisely remaining deaf to the tumult on terra ferma, and ruled by a doge almost as well reined-in as a Hanoverian king.

Venice's decline epitomises for Gilmour the travesty and tragedy of unification. "In 1797 it was a state in decline, certainly, but it need not have fallen much further. It might have recovered (like the Netherlands) and today Venice could have been (like the Hague) the capital of a successful small country" within the EU. Its unwilling incorporation into the kingdom of Italy was, he maintains, "an aberration" – as was the kingdom itself.