The one time I saw Mikhail Gorbachev in public was on November 9, 2014. I can pin the day down because it was the 25th anniversary of the fall of the Berlin Wall. We were in a very large, very crowded Berlin reception room, and he was sitting at a cocktail table, looking rather lost.

Gorbachev had been invited to this event as a trophy, a living, breathing souvenir of the 1980s. He was not expected to say much of interest. The fall of the Berlin Wall had happened by accident, after all; it was not something Gorbachev had ever planned. He had not set out to break up the Soviet Union, to end its tyranny, or to promote freedom. He presided over the end of a cruel and bloody empire, but without intending to do so. Almost nobody in history has ever had such a profound impact on his era, while at the same time understanding so little about it.

Gorbachev was born in Stalin’s Russia, but he began his career during the post-Stalin “thaw,” a moment when it became possible to acknowledge some truths out loud, but not too many. While he was still a student at Moscow State University, one of his closest friends was a Czechoslovak student named Zdeněk Mlynář. Both believed that communism could be reformed, if only the corruption and violence were removed. Mlynář’s convictions led him to become one of the leaders of the Prague Spring, a 1968 movement that started out by calling for “reformed communism” and “socialism with a human face.” That movement was crushed by Soviet soldiers, proving that corruption and violence were intrinsic to a system with no human face. Even cautious Czech reformers could not remove them so easily.

Still, the language of “reformed communism” continued to appeal to Gorbachev, who revived it when he became leader of the Soviet Communist Party in March 1985. But although he knew that Soviet society was stagnant and Soviet workers were unproductive, he had no idea why. In fact, his first instinct was not that the system needed democracy, or even free markets. Instead, he thought: Russians drink too much. Just two months after taking power, he restricted the sale of vodka, raised the drinking age, and started digging up vineyards. By some accounts, the resulting loss of tax income to the Soviet budget, plus the dramatic shortages—people were buying sugar and other products in bulk to make moonshine at home—were the tipping point that sent the Soviet economy into its final death spiral.

Real change had to wait until the Chernobyl nuclear catastrophe of April 1986. News of the accident was initially hushed up, just as bad news was always hushed up in the U.S.S.R. Hundreds of thousands of Ukrainians were allowed to march in the Kyiv May Day parade even as radioactivity spread silently across the city. But the scale of the disaster finally convinced Gorbachev that the real problem with his country was not alcohol, but its obsession with secrecy. His solution was glasnost—openness—which, like the anti-alcohol campaign, was originally meant to promote economic efficiency. Open conversation about the Soviet Union’s problems would, Gorbachev believed, strengthen communism. Managers and workers would talk about what was going wrong in their factories and workplaces, find solutions, fix the problem. No deeper reforms were needed, as he told a group of party economists early on: “Many of you see the solution to your problems in resorting to market mechanisms in place of direct planning. Some of you look at the market as a lifesaver for your economies. But, comrades, you should not think about lifesavers, but about the ship, and the ship is socialism.”