It took only 20 minutes before a couple in the third row of Lincoln Center’s Rose Theater meekly stood and snuck out of Shadowtime, Brian Ferneyhough and Charles Bernstein’s “thought opera” about Walter Benjamin. They were not the last to flee. While I’m hardly a Benjamin expert, I doubt he would have made it to the end of the performance.Benjamin was no stranger to the stage in his own time. In “A Berlin Chronicle,” he remembered his earliest trips the “monkey theater” before graduating to Carmen and The Merry Wives of Windsor. Years later, he championed his friend Bertolt Brecht in an essay on “Epic Theater.” Brecht’s ideal audience, wrote Benjamin, was thinking but relaxed, following “the action without strain”—and with “astonishment rather than empathy.”There was no danger of identifying with anyone in Shadowtime. The opera, after all, is less concerned with the philosopher than his philosophy. In the visually stunning climax, Benjamin finds himself in a kind of post-suicidal purgatory, where everyone from Einstein and Marx to the Golem and the Baal Shem Tov shows up to question him about memory, the future, and God. Benjamin is haunted by life’s big questions—”Are you prepared to be the new Rashi?” Gershom Scholem asks him early on—but he never gets to give very coherent answers.Moments later, the scene shifts inexplicably to Las Vegas, where a Liberace-like Lecturer issues odd aphorisms like “Around every corner is another corner. Around every corner is another coroner.” While no more comprehensible than the rest of the opera, the scene is captivating precisely because it remembers there’s an audience. Benjamin and Brecht expected a lot of their fans—I’ve read both to find myself equal parts frustrated and fascinated—but neither were difficult without a point. Shadowtime, for all the beauty of the music, often seems to strive for difficulty for its own sake, and doesn’t worry whether anyone can follow. Benjamin and Brecht sound like populists by comparison.