“To this day I get letters, maybe every two years, from top players asking me: ‘How do I quit? I want to quit like you did, and I can’t figure out how to do it,’ ” he says. “I tell them that it’s hard to go from being at the top of a field, because you really feel that way when you’re playing chess and winning, to being at the bottom — and they need to prepare themselves for that.”

He returned to M.I.T., rushed through what he acknowledges was a mediocre doctoral dissertation, and then became a researcher at the Federal Reserve — where he said he had good role models who taught him how to be, at last, “professional” and “serious.”

Teaching stints followed, before the International Monetary Fund chose him as its chief economist in 2001. It was at the I.M.F. that he began collaborating with a relatively unfamiliar economist named Carmen Reinhart, whom he appointed as his deputy after admiring her work from afar.

MS. REINHART, 54, is hardly a household name. And, unlike Mr. Rogoff, she has never been hired by an Ivy League school. But measured by how often her work is cited by colleagues and others, this woman whom several colleagues describe as a “firecracker” is, by a long shot, the most influential female economist in the world.

Like Mr. Rogoff, she took a circuitous route to her present position.

Born in Havana as Carmen Castellanos, she is quick-witted and favors bright, boldly printed blouses and blazers. As a girl, she memorized the lore of pirates and their trade routes, which she says was her first exposure to the idea that economic fortunes — and state revenue in particular — “can suddenly disappear without warning.”

She also lived with more personal financial and social instability. After her family fled Havana for the United States with just three suitcases when she was 10, her father traded a comfortable living as an accountant for long, less lucrative hours as a carpenter. Her mother, who had never worked outside the home before, became a seamstress.

“Most kids don’t grow up with that kind of real economic shock,” she says. “But I learned the value of scarcity, and even the sort of tensions between East and West. And at a very early age that had an imprint on me.”