History is usually written by a man with a pen, after the man with the sword has done his job.

The evidence is inarguable. Most of European history was written in blood long before it was recorded in ink after all.

Usually those who found themselves on the business end of colonialism and successive waves of religious persecution and enforced poverty have seen their stories written out of history by the victorious side. Having lost they were expected to stay silent while the winners staged their commemorative bonfires year after year.

You don’t need to tell the Irish this. We live in history in a way that’s utterly unique in Europe. Our past is ever present in how we live, where we worship (or don’t), what we give our allegiance to and even in how we speak.

The Reformation is unfinished business in parts of Ireland, despite having ended during the Enlightenment everywhere else. That makes our story terrific training for a budding historian.

Bestselling author Thomas Cahill, author of the just published "Heroes and Heretics," knows all about it. His own background is a classic Irish American tale, with his four immigrant grandparents arriving from Ireland to New York around 1900.

“They came from the midlands, Galway and Kerry,” Cahill tells the Irish Voice. “One of them was still an Irish speaker. Growing up I remember hearing them over and over at family gatherings insisting that no Catholic could ever be president.”

That blunt assurance fascinated Cahill, even after it came to an end in 1960 with John F. Kennedy’s election. What made them so sure they would always be defeated?

“I grew up being dimly aware that we were second class citizens. If we couldn’t be president there was something wrong,” Cahill said.

“That fact shaped my world-view and made me root for underdogs, which is what I’m often doing in my books in one way or another. I root for the people who are on the receiving end of other people’s caricatures.”

It’s the most Irish of impulses, to stand up for the marginalized, having been marginalized for centuries yourself. Cahill is in no doubt about the seismic event that disrupted Irish history and damaged their sense of themselves more than any other – the Great Hunger.

“So much was lost in that period. The Irish sense of themselves was lost to a large extent. They just became a poor and victimized and oppressed people, which is not at all what they had been previously.”

In 1970, when he had just turned 30, Cahill had a contract to write a book for Scribner’s titled "A Literary Guide to Ireland." What he noticed during his research trip there was that at the time there was very little public awareness of the achievements of great Irish writers. Systemic generational poverty had ensured that.

The further he traveled, the less people were aware of their own wider inheritance he says.

“Eventually we ended up at the sea in the west, at a Gaeltacht, where people could speak English well but they had to think about it to do it. We discovered we were in a completely different society,” Cahill says.

“These were cyclical people who lived with the seasons, with birth, copulation and death over and over again. They were not really part of the western world. So I began to ask myself the question, how did we become the people that we are in the west? Why do we think and feel the way we do, since these people seem so at one with a much older civilization?”

It was out of that that the "Hinges of History" ("Heretics and Heroes" is latest chapter in the series) emerged.

The Irish saved western civilization once only to see themselves almost written out, in fact driven near to extinction, later on. But Cahill knew he had found a great subject and his scholarship alerted millions to a story they had not known

“How the Irish Saved Civilization" (his celebrated study on the subject) was about this great moment in history that virtually no one knew about. We almost lost the literature of the western world except for the efforts of these strange people at the edge of Europe, who had just learned to read and write, because they took up the task of copying the books,” Cahill said.

“We’ve lost a lot of the books of the classical world but what we have is thanks largely to the Irish. They were working at the edge of the ancient world and the beginning of the modern world.”

Cahill freely admits his latest book "Heroes and Heretics" has been the hardest book to write by far of the series.

“What was difficult was that I realized no one writes about the Renaissance and the Reformation together. Everyone writes about one or the other,” he offers.

“But they occur around the same time and they arise from the same sources, which is the rediscovery of classical literature and culture. Up to that point for up to 1,000 years no one in the new world had read the New Testament in Greek. Nobody knew Greek in Europe. Everything was in Latin and that was it.”

Both periods got their start from the rediscovery of the classical world, but they went in completely different directions. That tension is wittily illustrated in the culture clash between the German and Latin worldviews.

Martin Luther left Germany only once in his life, Cahill says. “He went to Rome as a monk and he was horrified by what he saw. There were men kissing in the street and he’d never seen anything like that before.

“The truth of the matter is that even to this day you can go into a public restroom in Germany and have a picnic on the floor. You can’t do that in Catholic Europe.”

There’s an enduring philosophical and spiritual dimension to the clash that fascinates Cahill.

“Recently the German Chancellor Angela Merkel said, ‘I am so happy that I was born in the northern temperate climate and never had to take a siesta.’ That’s nice for Angela, but that means she’s missed out on a lot of pleasure, and not just sleeping.”

There is an assumption of superiority at work too, Cahill says. “The Germans have never gotten over the fact that the Romans called them barbarians. When they first appeared on the scene they could not read or write, they’re hunter-gatherers, they looked with great envy at the farms and vineyards of the Romans. They were on the wrong side of the Alps. I don’t think they ever got over how they were characterized in Latin literature.”

But the more complex societies become, the more Cahill says he looks for something relatively simple.

“I have come to believe there are really only two forces in the world, kindness and cruelty. A civilization can go either way and no one is above the possibility of cruelty, nor is kindness impossible to anyone,” Cahill offers.

“What people will do in a particular situation is very hard to know in advance. In the aftermath of the Reformation, Catholics decide to kill as many Protestants as possible and Protestants decide to kill as many Catholics as possible. It finally stopped everywhere except Ireland.”

In the Enlightenment people dared to ask themselves, 'Are we really going to have to keep on doing this? Isn’t there some other way?'

The solution turns out to be tolerance. I may not like what you have to say but I’m going to let you live. To us it seems so obvious but to them it was revolutionary.

Cahill had an unforgettable lesson in how the forces of history work in his own office when he became acquainted with Jacqueline Kennedy Onassis, who was working as an editor at Doubleday at the time.

“We were colleagues. I was the director of Religious Publishing and she was an editor there, a very good one. We had offices next to one another and we ended up conferring a lot. I liked and admired her tremendously,” Cahill recalls.

For a historian it must have been especially fascinating to come within Kennedy’s orbit.

“Many people were afraid of her because she was the most famous woman in the world. Most people couldn’t speak to her normally, which meant that she was very lonely, even with her colleagues. That was not what she wanted.”

In conversation Cahill always found her to be what he called a blasted human being.

“Her husband’s head was shot to pieces and was in her lap. I don’t think you recover from things like that,” Cahill feels.

“She was in her early thirties when that happened. I believe it’s why she died young. She had been battered by history.”

As for his immensely readable new book, Cahill puts it this way: “Most of the heretics are heroes and most of the heroes are heretics.”

Living with that contradiction is a traditional Irish skill.

Heroes and Heretics, Doubleday $29.95.