In recent years Joseph Perella, a giant of the American private equity world, has become obsessed with Italy's history. The periods that normally attract attention, such as the Renaissance or Roman empire, are not what interests Perella. Instead, what has sparked his passion is a saga that is relatively unknown, namely how ordinary Italians treated their Jewish minority during the Second World War.
Mr Perella (whose parents hail from Italy) has shared his obsession in a new documentary that he has financed, along with a group of powerful Italian-American business leaders. This film relates how men such as Gino Bartali, an Italian cycling legend, worked with hundreds of other largely unknown Italians to keep thousands of Jews alive during the Holocaust.
It is a fascinating project. For one thing, it is a powerful reminder of how ethnic heritage creates networks among the US business elite.
The consortium of Italian Americans that Perella pulled into this $1.5m project features people such as Kenneth Langone (head of retailer Home Depot), Maria Bartiromo (the television journalist) and Joseph Tucci (head of EMC, the computer data storage company).
But the more important issue is the subject of the documentary. I knew almost nothing about how Italians treated Jews during the Holocaust.
As a child in North London, I heard Jewish friends talk about the horrors inflicted on the Jewish communities in Germany, Austria and Poland. I also heard tales of heroism in places such as Holland, and watched films such as Schindler's List. But until I saw the Perella film, I did not know that about 80 per cent of the Jewish population in Italy survived the war.
And while that high survival rate partly reflects the fact that the Nazis never completely controlled Italy, the attitude of the Italian population was also crucial. Although some Italians co-operated with the Nazis to send Jews to concentration camps, many others created networks to protect them, at great personal risk.
And despite the Vatican failing to speak out against the Holocaust, Catholic priests and nuns played a central role in these rescue missions, in sharp contrast to those in countries such as Poland.
Some of these Italian rescuers are already in the history books: the documentary highlights how Bartali carried false documents for Jews across Italy as he "trained" on his bike, cycling for miles between monasteries and churches. But many other Italian protectors have never been celebrated. And that reflects another historical quirk: although Italy is often portrayed as a voluble nation, the rescuers of the Second World War were often quiet about their role. So much so that Oren Jacoby, the film-maker, initially wanted to call the documentary Don't Talk About It, before changing it to My Italian Secret.
Quite why this pattern arose is a matter of some dispute. One factor was that the Italian Jewish community was well integrated and only numbered some 50,000 (compared to three million in Poland). Another may have been a cultural propensity for ignoring rules: when faced with Nazi orders to hand the Jews over, many Italians simply found creative ways to flout them.
The tale is worth celebrating - and not just among people of Italian descent or the Jewish community. In today's world we tend to focus so heavily on human brutality that it is often easy to forget that humans have a capacity for doing great good as well. Insofar as we celebrate heroes, they tend to be towering figures who often assume near-superhuman status in Hollywood tales. In reality, when people get sucked into evil, it rarely occurs as a result of a binary choice; instead, a long series of tiny, half-conscious decisions creates a slide from good to bad. Similarly, when societies combat evil, this does not always occur because of dramatic resistance from visible heroes but as a result of quiet decisions taken by ordinary people to say "no". "What this film shows is that if you are not indifferent then you can make a difference," Perella observes. "But the remarkable thing about this story was that most of the people involved did not want to talk about it." Which is why stories like this need to be told as loudly as possible. Particularly in a world where genocide keeps happening, over and over again - and where it is the tales of evil, not good, that children overwhelmingly tend to hear.