Prime Minister Matteo Renzi announced early Monday morning that he would resign, following a referendum on constitutional reforms. Below, Jason Horowitz’s profile of the young, charismatic politician from earlier this year, during more optimistic times.

“They haven’t arrived?” asked Matteo Renzi. The 41-year-old Italian prime minister, dressed in a tailored navy Armani suit, swept into a reception room in Palazzo Chigi, the frescoed sixteenth-century seat of power in Rome, expecting to bestow the thanks of a grateful nation on a group of Italian skiing champions. The skiers, to his astonishment, were running late.

Renzi exudes confidence and an almost mischievous nonchalance—a combination that has beguiled, infuriated, and defined Italy since he became its youngest leader two years ago. On this summer day he spun on the heels of his polished black shoes and clapped his hands into the praying gesture of Italian disbelief. “Marvelous,” he said.

In a country—and a continent—known for taking its time, Renzi moves at a breakneck pace. He hates sitting still. A fraught photo shoot last year prompted the photojournalist Alex Majoli to complain to Renzi’s press secretary that “only one other person ever made me work as hard for a photo: Rihanna.” Before one of our interviews, Renzi, having just had breakfast with his wife, Agnese Landini, excused himself to brush his teeth—and ran at full clip to the sink. In meetings he is known for being brusque, with elbows-on-the-table and bouncing-knee intensity. His friends say the thing that truly enrages him is wasting time. (When, during a trip to Boston and Cambridge last March, an aide held up his motorcade to remind Renzi he had forgotten to film a progress report for his millions of social-media followers, the prime minister practically exploded: “Fuck, you’ve got to tell me!”) Impatience is stamped on Renzi’s face. With his soft features and infectious laugh, he can be disarmingly charming, but Renzi’s default expression is one of restlessness: lips pursed, hyphen-short eyebrows arched, and dark eyes glaring with a dubious let’s-get-on-with-it look.

That sense of urgency is a necessity for a leader seeking to change a country that has had 63 governments in 70 years. But it is also required to rescue a European Union in existential crisis, as elite estrangement from economically alienated citizens has fueled a populist rage most clearly manifested in Britain’s momentous decision to leave the E.U. Renzi may be the man for the moment. A pure political animal who in his rise to power presciently tapped the mad-as-hell vein running through Europe, Renzi campaigned under a superhero nickname: Il Rottamatore, the Demolition Man of dusty institutions. But once in office, Renzi became Stability Man, seeking measured reforms—liberalize the job market, improve education, and legalize civil unions for same-sex couples. He has an affable, Everyman quality about him—backslapping provincial charm is one of Renzi’s most powerful political weapons—but his eyes betray constant calibration and light up when he waxes poetic about “working the levers inside the system.”