How Gorbachev Changed the World

Few leaders have had as profound an effect on their time as Mikhail S. Gorbachev, the last leader of the Soviet Union, who died this week at 91. It was not Mr. Gorbachev’s intention to liquidate the Soviet empire when he came to power in 1985. But after little more than six tumultuous years, he had lifted the Iron Curtain and presided over the dissolution of the Union of Soviet Socialist Republics, ending the Cold War. Guest: Serge Schmemann, a member of The New York Times’s editorial board.