Varoufakis says he took the job because, after years of articulating a solution to the crisis, he said he felt he didn’t have a choice. “In the 1980s, I was incensed by apartheid. Some people could forget about it; I couldn’t forget about it. It’s not because I am morally superior, I just couldn’t forget about it. Similarly, in the case of the 2008 crisis, it was the idiocy of it: This was a crisis that was unnecessary.”

Varoufakis traces his political consciousness to his childhood in “the junta era” — the years when Greece was ruled by dictatorship. “It was very hard to avoid being political,” he said. “It was all around you.” His father, he said, was raised as “a liberal enlightenment person, not a left winger,” but when he immigrated to Greece from Cairo in the late 1940s, the royalist-communist civil war was underway. One day, the police roughed him up but said they would release him if he signed a denunciation of communism. “He said, ‘Look I am not a Buddhist, but I would never sign a denunciation of Buddhism,’ ” Varoufakis said. “He read Rousseau at 13 years old, and he knew about civil liberties.” He ended up in a concentration camp with communists — and joined the Communist Party, which made finding work nearly impossible. Eventually, he got a low-paying job as a personal assistant to the owner of a steel company, and today, at age 90, he is its chairman. Varoufakis’s mother, a biochemist, made “a pittance,” he said, because she was a woman. She became involved in the feminist movement in the 1970s. Varoufakis was also a political activist from a young age. When he began his career as an academic at the University of Essex, he said, his slogan became “subvert the dominant paradigm,” which some of his students later put on a T-shirt.

Varoufakis left England in 1988 to teach at the University of Sydney, where he began a series of conversations about the global economy with the economist Joseph Halevi, the two of them among academics in their field who contested the notion then popular that the world had entered a new phase of “perpetual growth,” what the former Federal Reserve chairman Ben Bernanke called the “great moderation.” After the crash, Varoufakis decided to put those ideas into a book for a popular audience titled, “The Global Minotaur,” which presented the world, and Europe, as perilously yoked to the fluctuations of the American economy. When the crisis finally reached Greece, Varoufakis began working with the British economist Stuart Holland and, later, the American economist James Galbraith, on a pamphlet titled, “A Modest Proposal,” which identified four major crises in Europe — in banking, public debt, underinvestment and social welfare — and proposed solutions to each. “Europe is fragmenting,” they wrote. “As this happens, human costs mount, and disintegration becomes an increasing threat. . . . The fallout from a eurozone breakup would destroy the European Union, except perhaps in name. And Europe’s fragmentation poses a global danger.”

He told me that he still felt that way. The crisis that began in 2007 was just as bad as the Great Depression that started in 1929, and it was far from over. “We need a New Deal for the globe,” he said, “at least for Europe.” But when he sought to make his case in interviews and speeches across Europe these past months as finance minister, while also mounting a moral argument for easing the suffering of Greece as well as other southern European countries, his European counterparts were exasperated. They were frightened, too, by the prospect of Varoufakis serving as inspiration for leftist movements elsewhere — especially in Spain, where Podemos, a leftist party led by activists who also oppose austerity policies, has made significant inroads. At the February meetings, the European financial leaders pushed back by insisting on austerity. Aristides Hatzis, a professor of philosophy in Athens, says that Varoufakis found himself “where no one was interested in life in the eurozone in the long term — they were only interested in specific details about the way Greece was going to pay its debt.” Because Varou­fakis is clever, Hatzis says, he adjusted to this reality and changed course. He was also forced to make many concessions.

The American economist Joseph Stiglitz, a Nobel Prize winner, describes Varoufakis’s situation as “absolutely impossible.” “There is an obsession among policy-making economists in Germany about fiscal balance,” he says, “compared to unemployment, inequality, economic growth, financial stability.” When Greece received its first bailout in 2010, the Europeans insisted on severe austerity while predicting that Greece’s gross domestic product would shrink by only 4 percent. Over five years it shrank 25 percent. (Stiglitz says that he tells his students that if their economic models and forecasts were that bad, he would give them an F.) By 2011, according to Stiglitz, the European leaders admitted they needed a new strategy. “They never delivered,” Stiglitz told me. “In a way, Europe has reneged on their promises over and over again, and Yanis and this new government have to pick up the pieces.”

When I met Varoufakis in late March, his popularity remained buoyant, at least on the street, despite the increasingly caustic criticism of him at home and abroad. It was a gray Sunday morning in Athens, and only a few men sat in cafes drinking coffee and smoking. “Keep going, Yanis,” said a taxi driver as we walked to a cafe near the Acropolis. “Good job,” another said. Varoufakis smiled and thanked them. Before turning inside, a man stopped him and shook his hand. I asked if it was always like this. He said, “Yes, all the time.”