MONTREAL - So how exactly did Pierre Elliott Trudeau go from vowing to create an independent Quebec to becoming the scourge of sovereigntists?
The notion that people might flip-flop on such a fundamental question as whether Quebec should remain in the country is one that has befuddled and frustrated Canadians for years.
The fact that Canada's current interim Opposition leader, Nycole Turmel, once held a Bloc Quebecois membership card is just a recent variation on that theme.
There was also fevered speculation about Michaelle Jean's loyalty when she was named governor general. Federal politicians like Maxime Bernier and a number of new NDP MPs, along with former parliamentarians like Jean Lapierre and Lucien Bouchard, have also held varying allegiances over time and been grilled for it.
And then there's Trudeau, a staunch Canadian nationalist who has been described as the most federalist of prime ministers and who introduced the modern Constitution.
Some Canadians might struggle to believe that, in his younger years, even Trudeau was a Quebec separatist.
Max and Monique Nemni give a detailed explanation of Trudeau's metamorphosis in their new book, "Trudeau Transformed: 1944-1965 The Shaping of a Statesman." The second in a two-volume series, it goes on sale in its translated English version Tuesday, several weeks after the release of its original French version.
The Nemnis, who were friends of Trudeau in the 10 years before he died in 2000, have tracked the evolution of Canada's most famous flip-flopper in a biography that offers a textbook example of how political thought can change.
In their first volume, "Young Trudeau: 1919-1944, Son of Quebec, Father of Canada," they looked at how Trudeau was initially influenced by the clerically dominant, conservative trend in Quebec thought.
That book, published in 2006, said he seemed to favour ethnic nationalism; he even vowed in a 1936 essay that he would lead an army "to declare the independence of Quebec" in 1976.
Ironically, that would be the year that the federalist firebrand Trudeau would see the province bring the sovereigntist Parti Quebecois to power under his nemesis Rene Levesque.
In "Trudeau Transformed," the authors exhaustively researched Trudeau's private and public papers to show how he became the man with whom Canadians are familiar. That book picks up Trudeau at age 25 and looks at his life until his election to Parliament 20 years later.
"Throughout these years that we describe in our book, 1944 to 1965, we see this man changing constantly but this kind of change isn't the change of a guy who is an opportunist, adapting to circumstances in order to seek power," says Max Nemni.
"Far from it. It's a guy adapting to circumstances in order to act within these circumstances and do the best that he can."
Monique Nemni said that when Trudeau was growing in Quebec, he subscribed to the values that were given to him by the intellectuals and clerics in his sphere.
"So he was a separatist like the others were, like the elite was," she said. "Because Trudeau was Trudeau, and he really carried things as far as he could, he became one of the leaders in that sort of thing.
"But then he went to Harvard. That was a big shock. He didn't just convert in one day. It took him a while."
Exposure to different ideas from some of the big thinkers at the time, at Harvard and later the prestigious London School of Economics, gave the young Trudeau ample food for thought as did his extensive world travels.
It was at Harvard that the seeds of doubt about his support of separatism surfaced, and he began to see the benefits of "Constitutionalism" and the potential dangers of nationalism.
While Trudeau had initially embraced certain principles of political philosophy and economics he learned at the university because of their potential benefit to Quebec, further consideration of those principles over time led him to conclude that Quebec was better off within Canada.
Among the professors at Harvard who left an impression were John Henry Williams, a noted economist who contributed to the construction of the post-Second World War global financial system, and Alvin Harvey Hansen, another economist who was a disciple of John Maynard Keynes.
Harvard taught Trudeau that people were not just some mass to be herded around by the elites, the book says.
At the London School of Economics, he took hundreds of pages of notes in the courses of another mentor, the renowned intellectual Harold Laski, who impressed him with his concepts of equality and freedom.
Experiences in academia and through his travels expanded Trudeau's horizons and challenged what he already knew, the Nemnis said.
"Progressively, he becomes the man that we know as prime minister," Monique Nemi said.
The book illustrates Trudeau's completion of the tranformation to federalist. Those basic values, once adopted, stayed with him for the rest of his life. The book illustrates some of those principles by quoting Trudeau's famous "The New Treason of the Intellectuals" article in a 1962 edition of "Cite Libre."
There, he tells separatists that the idea that every nationality should have its own country is "absurd": "Because every national minority will find, at the very moment of liberation, a new minority within its bosom which in turn must be allowed the right to demand its freedom."
The Nemnis point out that some of Trudeau's youthful values never changed — including the primacy of the individual and the idea of charity, which they say was reflected in his concept of the Just Society.
Both authors said they were surprised at the relevancy of their history, which is published by McClelland and Stewart. They agreed there might be some parallels between Trudeau and those new NDP MPs from Quebec.
Political scientist Bruce Hicks says changing times and values likely influenced some former sovereigntists to ally with the federal New Democrats for the May 2 election.
He pointed out that the sovereignty movement had evolved from what it was when Trudeau was young as well as when it was later led by Levesque.
Hicks, who teaches at both Montreal's Concordia University and Universite de Montreal, said Turmel's Bloc membership got little reaction in Quebec because people have lived with the sovereignty debate through two referendums and sometimes within their own families.
"It doesn't strike the same emotional chord as it does, let's say, in Alberta where the word 'separatist' has a certain resonance that inflames some passions."
He said many people aren't focused on one issue alone and some sovereigntists may have felt the NDP's social-democratic leanings were more in tune with their objective. Sovereignty isn't a hot debate right now.
"People don't put their lives on hold," he said.