Thinking the Twentieth Century, the last book by the late NYU historian and intellectual provocateur Tony Judt, is the product of an unusual collaboration. Before Judt was diagnosed with Lou Gehrig’s disease in the summer of 2008, he was planning to follow up Postwar, a now canonical account of Europe since 1945, with a history of 20th-century social thought. But the incurable neurological disorder made it impossible for him to write.

Yale historian Timothy Snyder, author of the critically acclaimed Bloodlands: Europe Between Hitler and Stalin, and a longtime friend of Judt’s, suggested that Judt talk the book out with him, instead. Most Thursdays, for most of 2009, Snyder visited Judt’s apartment in Manhattan’s Washington Square and recorded their conversations. The men worked on the final product until a couple weeks before Judt’s death in August 2010, at the age of 62. The result mixes history and ideas, Judt’s personal journey from a young Zionist to a lapsed Marxist, and current politics. Each chapter—from the first, on Judt’s Jewish upbringing, to the last, in which he makes his argument for a renewed social democracy—begins with an extended biographical section in Judt’s words, followed by a dialogue between him and Snyder, who asks questions and offers his own thoughts.

Judt’s mind and elbows are as sharp as ever. At turns, he is biting about colleagues and ex-wives, the political right, and—no surprise to those who followed his political writing—Israel. Judt gained wide notoriety for a 2003 New York Review of Books essay that argued that to remain a democracy, Israel needs to morph “from a Jewish state into a binational one.” The New Republic subsequently dropped Judt as a contributing editor, and Judt’s career as a Francophonic, British, Jewish, New York public intellectual, so to speak, flourished. I sat down with Snyder last week in New Haven to talk about Judt, their friendship, and their new book.