Everything in Strom Thurmond’s long political career springs from one day in 1912, when a 9-year-old wise beyond his years accompanied his daddy to a stump speech.

Speaking that day, says Emory professor Joseph Crespino, were the virulently racist governor, Cole Blease — known not just for opposing his critics but flaying them verbally — and the man Strom Thurmond’s father, Will, supported: Ira Jones, a former speaker of the state House and chief justice of the S.C. Supreme Court.

It was then that a 9-year-old boy decided to run for governor someday, United States Sen. Strom Thurmond remembered in an interview almost 70 years later.

“They put up a platform for them to speak on and brought a big pitcher of water,” Thurmond told an interviewer in 1980. “Jones, he made a good talk, a literary talk; but he just didn’t stir the people.

“Well, Cole Blease was a fiery kind of fellow and a great orator. You could see people who were not really the thinking people who were carried away by the speech. I could see then the influence he was going to have over the state for being such a good speaker . . .

“After hearing him speak, I knew that I was going to run for governor. And I was going to learn to speak, and I never would let a man do to me like Blease did Jones that day.”

Crespino, a history professor at Emory University in Atlanta and author of the book “Strom Thurmond’s America,” says that everything comes down to this day: the “deep, dark secrets” of Thurmond’s sometimes-profligate youth, the verbal “bomb-throwing” and filibustering of the segregationist period, the pragmatism of the post-civil rights era and the reinvention of the aged Thurmond as a sweet old son of the South.

In his book, Crespino focuses on “material other biographers have noted but not seen the significance of,” such as that defining Blease-Jones debate. The debate, Crespino says, was where the young Thurmond first witnessed “the power of the demagogue.” The impression was one that lingered throughout Thurmond’s 100 years of life and was an impression upon which he put his personal stamp.

If Thurmond admired the spirit of Cole Blease, he did not entirely mimic it. Thurmond, Crespino says, always tempered his zeal with pragmatism.

How else to explain how an FDR Democrat became a Dixiecrat became a Republican courted by the likes of Richard Nixon, Barry Goldwater and Ronald Reagan?

How else to explain that, unlike other Southern politicians who publicly apologized for their earlier segregationist zealotry, Thurmond never said he was sorry, never publicly acknowledged the black daughter he had sired with a family maid during his youth – although he paid her way through school and visited her regularly?

Throughout his career, Thurmond merely shifted his tactics, not his beliefs — something Americans were used to because his political life had been one of constant, pragmatic shifts. In this way, he was able to appeal to a broader base and to limit the effects of his foes — especially African-American foes, Crespino says.

Crespino says that Thurmond didn’t invent the politics of the current day with his actions and rhetoric, but he undoubtedly had a great hand in shaping it.

Thurmond’s voice still echoes in the political rhetoric of the current day.

Crespino argues that Thurmond’s political progeny — people such as Reagan and Bush political adviser Lee Atwater and former Mississippi Sen. Trent Lott, who twice has claimed publicly that the world would be a better place if Strom Thurmond had won the presidency in 1948 – and the hard-line political tactics, the “kind of coded racial appeals” that they have espoused, “can be seen as legacies that came from Strom Thurmond.”

When people remember Thurmond only as “one of the last Jim Crow demagogues . . . what we forget is that he was also one of the first Sunbelt conservatives” – a man who made some of the first steps in “reinventing GOP conservatism.” For example, Crespino says, Thurmond was working with the religious right long before it became the Religious Right.

Unlike those who claim that Thurmond underwent a significant emotional transformation during his later years – and, thus, might be forgiven for his earlier impolitic or embarrassing ventures — Crespino is not interested in what “happens in Thurmond’s heart” but in his public presence.

To those critics who have claimed Crespino does not make the case that today’s America is “Strom Thurmond’s America,” the author says: “I’m not saying we still live in Strom Thurmond’s American today – I don’t believe we do.

“(But) the legacies of segregation are still very real.”

To understand how segregation shaped what has become the modern South – the modern America – “we have to know Strom.”

Uninformed criticism is “what you sign up for” when you write a book about such a public and controversial figure, says Crespino, who also wrote “In Search of Another Country: Mississippi and the Conservative Counterrevolution” and co-edited “The Myth of Southern Exceptionalism.”

“I’m not wringing my hands (at being misunderstood). I’m not saying ‘woe is me,’” because critics miss the nuance inherent in Thurmond’s tale.

Having grown up in small-town Mississippi during the 1970s, when “the legacies of segregation were still very real,” and coming of age during the shaping of the modern Republican Party, Crespino is curious about the shaping of the modern political landscape.

All he wants to do is what he says almost everyone who has met the senator ever has done: tell his own tale of Strom Thurmond. Crespino tells tales, too, but places them in the context of current Southern – and American – politics.