The German Jewish intellectual Walter Benjamin, born in Berlin in 1892, dead by his own hand on the French-Spanish border in 1940, remains a man of mystery. Anything but prominent in his lifetime, he has emerged in recent decades to unvarnished acclaim as the greatest thinker of the 20th century in fields ranging from philosophy to sociology, aesthetics, literary theory and criticism, and a half-dozen more. This in itself is mysterious. Among the ranks of mid-century Central European intellectuals, the reputation of Benjamin’s contemporaries and colleagues (with the possible exception of the Frankfurt School philosopher Theodor Adorno) continues to shrink; his continues to rise and rise. The number of books and articles devoted to him is staggering; a huge new biography, Walter Benjamin: A Critical Life, co-written by Howard Eiland and Michael W. Jennings and published by Harvard, is only the latest addition to a seemingly unending stream.

How to explain the Benjamin vogue? Eiland and Jennings cite such cultural signposts as the radical student movement of the 1960s and the attendant revival of Marxist thought. But 60s radicals were hardly great readers, and Benjamin’s writings are, to say the least, maddeningly opaque and often altogether inaccessible. As for his Marxism, such as it was: if that is the main point of attraction, by rights the real culture hero should be his contemporary Herbert Marcuse (1898-1979)—once famed as the “father of the New Left” but, these days, decidedly not a name to conjure with.

More likely, Benjamin owes his fame to the rise of cultural studies and its various academic subdisciplines: post-modernism, post-structuralism, women’s and gender studies, and the rest of the lot. In these precincts, Benjamin’s gnomic style may well count as a plus, an outward sign of inward profundity that, simultaneously, invites the most fanciful flights of interpretive ingenuity. Likewise contributing powerfully to his allure is the sorry story of his life. Quite apart from his tragic end—he swallowed poison while fleeing from Nazi-occupied France—he was always the frustrated outsider par excellence, the very type of the marginal man. Indeed, had he lived, one can hardly picture him as a happy soldier among the academic janissaries of contemporary cultural studies.

My own interest in Benjamin arose from my work in the early 1950s on the pre-World War I German youth movement, in which he had been a passionate but by no means leading member. In connection with this project I met some friends of his youth, including, in Germany, the pioneering educator Gustav Wyneken, who had served as one of his early gurus. In Italy, I encountered a number of his former associates in the radical youth journal Der Anfang. In Jerusalem there lived the librarian and poet Werner Kraft, an early friend but later a critic, and above all Gershom Scholem, who had been Benjamin’s closest friend both in Berlin and later on and who would become, with Adorno, the figure most responsible for launching his posthumous reputation.

The Scholems’ living room in Jerusalem was dominated by a drawing—Paul Klee’s Angelus Novus (1920)—which had been owned by Benjamin and played a central role in his thinking, and which Scholem had inherited after the war. (It is now in the collection of the Israel Museum.) At tea in the Scholem household, sooner or later, the conversation would turn to the Benjamin Question. Yes, he was highly educated, widely read, and engaged in diverse areas of inquiry. Yes, his ideas (as in his best-known essay, “The Work of Art in the Age of Mechanical Reproduction”) were often original, and there were flashes of genius. But in what precisely did his genius consist? Had he produced a new philosophy of history, proposed a fundamentally new approach to our understanding of 19th-century European culture, his main area of concern, or revolutionized our thinking about modernity? The answers I received weren’t persuasive then, and the answers provided in the vast secondary literature of the last decades have done no better....