At first glance, Theodor W. Adorno’s critical social theory and Gershom Scholem’s scholarship of Jewish mysticism could not seem farther removed from one another. To begin with, they also harbored a mutual hostility. But their first conversations in 1938 New York were the impetus for a profound intellectual friendship that lasted thirty years and produced more than 220 letters. These letters discuss the broadest range of topics in philosophy, religion, history, politics, literature, and the arts...