CHICAGO —

To understand why Theo Epstein would leave his one-time fantasy job — he grew up in Brookline, Mass., about a mile from Fenway Park — you first have to probe the psyche of big thinkers and dreamers.

When Epstein became the youngest general manager in baseball history at age 28 years, 11 months, his father Leslie told the Boston Globe:

“It’s a little dizzying, that’s a good word. But at Theo’s age, Alexander the Great was already general manager of the world.”

Indeed he was. And he also was undefeated in battle as he conquered what then was considered the whole world.

Now Theo Epstein — if reports are correct — attempts to conquer the baseball world. Ten years after cracking the seemingly impossible Curse of the Bambino in Boston, he takes on the arguably more challenging task of crushing the Curse of the Billy Goat.

To overcome both would make Epstein the baseball equivalent of Alexander the Great — the smartest and greatest general manager in history.

Epstein comes from a family of motivated doers who expect and reward imagination and accomplishment. His grandfather Phillip and twin brother Julius wrote the screenplay for “Casablanca.” His father was a Rhodes scholar.

Cub fans will argue it will take all Theo Epstein’s creativity to win a World Series at Wrigley Field — and maybe more. After all, the Boston drought lasted “only” 86 years, the one on Chicago’s North Side has existed for 103.

It is the baseball Everest. But then Hannibal drove his elephants over the Alps, didn’t he?

If Epstein is looking for history lessons on the Cubs, he already has done research in Boston.

The situations are so similar it is eerie.

But cures for curses, believed or imaginary, are like fighting an unseen enemy. Perception becomes reality, until proven otherwise.

Over the past century, Cub management teams variably have ignored the so-called Curse or embraced it with holy water and parading a goat around Wrigley Field.

Now they confront it head-on with Epstein, who already has shattered one baseball myth with his mastery of baseball math known as sabermetrics.

It took him two years with the Red Sox to win a World Series and three years to win again, raising expectations to a level that even he couldn’t maintain.

So what will he find when talking to fans at the nearest Wrigleyville Starbucks?

That they are great doubters, to the point of being inbred from generations of failure. And that many Cubs fans, in fact, have cuddled up to the notion of being “loveable losers.”

It is not unlike what Epstein found in Boston, except this time he comes with a “genius” label already attached.

Attaining genius status sometimes is easier than maintaining it, as he discovered when his star began to fade in Boston.

Some will complain Epstein became complacent and soft from a bloated payroll, so perhaps the challenge of a new Curse will rekindle his creative juices.

Truth is, that while the pressure in Chicago will be nearly overwhelming, it is nothing compared to his first days as general manager in Boston.

Back then, he was returning to his hometown, a city that in the summer lives and dies with only one topic — the Red Sawx. There is no second storyline. Even a big Bruins trade would be a third or fourth news item.

Chicago has two baseball teams and, while White Sox fans may not believe it, they are treated mostly equal, especially now that the South Siders have ended their own championship drought (one that actually lasted longer than Boston’s, but without the hype).

He will be entering the blue-collar, big-shoulders, hog-butcher-to-the-world environment that will be foreign, certainly one completely different from provincial New England thinking where Epstein’s Yale degree was considered a pedigree.

Yes, he will be taking over a team that hasn’t won in decades, in an outdated ballpark, with a built-in fan base and new ownership committed to winning — just like in Boston. But he also will discover it is not as easy as bringing his Boston blueprints along and building an exact replica from them.

Chicago is different and so are the ballpark and the circumstances — and the lower inherited talent level. They play a lot of day games in Chicago, some say too few and a growing number say too many as the debate over players’ body clocks thrives.

Chicago has Wrigley Field, perhaps as charming to outsiders as Fenway Park is. But it also is crammed, badly in need of expansion to keep up with baseball’s big markets in a recessionary economic environment.

Chicago has a mayor and aldermen and neighbors — not to mention a White Sox fan as governor in a near-bankrupt state — to contend with, not all of them as unified in their love as officials might be in a one-team city.

And yet, the baseball business model is the same — you win with talent. And now we will see how much talent Epstein really has in gathering baseball talent, whether his new way of looking at an old game really works.

This will be a first for the Cubs, who always have been run the old-fashioned way, even as the new wave — one in which statistics matter as much as scouts — swept over baseball.

Can the Cubs Curse be conquered? Can those all-knowing baseball gods finally give up whatever cruel suffering they have imposed? Just remember, it was Aristotle — tutor to Alexander the Great almost 2,400 years ago — who once said: “The gods too are fond of a joke.”