A school photograph taken in Hamburg in 1879 shows thirteen-year-old Abraham Warburg among his classmates, conspicuous for his dark coloring and the mischievous, bemused expression on his face. Aby is obviously a handful. He dominates this solemn group portrait as definitely as he dominated his boisterous and numerous family, seizing attention with his quick wit and his tempestuous moods.

Aby knew his own mind. At thirteen, around the time the photograph was taken, he made a deal with his twelve-year-old brother Max: if Max would promise to buy Aby all the books he wanted for the rest of his life, Aby would hand over his designated position in the family bank. Both brothers were as good as their word. Max Warburg, the illustrious banker, would later declare that “this contract was certainly the most careless of my life,” and it would cost him dearly over the years. By 1914, Aby Warburg’s personal library numbered 15,000 volumes, many of them manuscripts or rarities from the earliest days of printing. Max and the three younger Warburg brothers, Felix, Paul, and Fritz, continued to subsidize their eldest brother’s bibliomania up to and beyond his death in 1929. Aby called the resulting collection his Kulturwissenschaftliche Bibliothek Warburg or Warburg Library of Cultural Science, and he intended the choice and the arrangement of the volumes on the library’s shelves to create bridges between disciplines that he himself saw no reason to separate.

Aby was also crazy. Today we would call him bipolar; he alternated periods of elation with dark despondency. Considering the circumstances under which he lived, a wealthy, hard-driven Jewish citizen of the German Reich and the Weimar Republic, he had much to be despondent about. Emily J. Levine’s book details the contradictions and confusions of Jewish life in Hamburg, with ancient religious traditions suddenly vying with modern currents of thought, and ancient caution competing with tentative hopes when Jews at last began to breach the barriers of anti-Semitism in German society. Focusing on Aby Warburg’s library and two of its most illustrious users, the philosopher Ernst Cassirer and the art historian Erwin Panofsky, she reveals the ways in which the distinctive qualities of a single place conditioned the development of ideas in a larger sense to create a “Hamburg School” of thought, a school intimately connected with Jewish experience in Imperial and Weimar Germany. Her supremely well-educated, well-connected protagonists would eventually have the means to escape from Germany and the worst ravages of National Socialism, as, at the very last possible minute, did Aby’s books; but theirs is still a tragic story.

In arguing for the importance of place and social setting in the formation of ideas, Levine crosses as many scholarly disciplines as Warburg’s Library of the Science of Culture did in its heyday. Dreamland of Humanists begins by outlining the history of Hamburg (roughly between the revolutions of 1848 and the advent of the Nazis) together with its distinctive forms of cultural life. Through detailed analysis of Warburg, Cassirer, Panofsky, and the Hamburg School of thought that formed around them, Levine illustrates how this commercial city, for all its apparent limitations, turned out to provide a uniquely hospitable setting for the exchange of ideas. The novel propositions that this trio of thinkers would formulate about art, symbolism, and imagery have shaped more than the course of modern art history; they are also unwittingly responsible for Dan Brown’s improbable hero Robert Langdon, whose fictitious field of expertise, “symbology,” is a direct outgrowth of the “pathos-formulas,” “symbolic form,” and “iconology” developed by the Hamburg School of philosophy and history of art in connection with the Warburg Library of the Science of Culture.

Hamburg was a rough, gritty northern European port, with rotten weather and a superb location. From the thirteenth through the seventeenth century, it belonged to the commercial cartel known as the Hanseatic League, and owing to those origins as an independent city-state it continued to go its own way after the political unification of Germany in 1870. At the end of the fifteenth century, Hamburg was one of the places where Sephardic Jews settled after their expulsion from Spain in 1492 and Portugal in 1497. There they were compelled to work as moneylenders because so many other professions were barred to them. From the mid-sixteenth century onward, Hamburg’s Christian community adopted an austere Protestantism that meshed with a correspondingly austere version of Judaism. For Christians and Jews alike, then, personal aspirations were kept in line by an overriding emphasis on community.

By profession, the citizens of Hamburg were sailors, shopkeepers, innkeepers, and merchants rather than landed aristocrats, and their city therefore lacked the kinds of cultural institutions that kings, bishops, and aristocrats tended to foster, amenities such as universities, opera houses, art collections. When cultural institutions finally came to Hamburg, they came late, in the nineteenth and early twentieth centuries, at which point they grew out of a different social stratum, the merchant class, and responded to different, more private stimuli, as expressions of personal hospitality and ancient Jewish traditions of self-help. As Levine shows, Jewish philanthropy played a fundamental role in creating the cultural life of nineteenth- and early-twentieth-century Hamburg, a cultural life that depended almost entirely on private patronage and aimed at a more egalitarian, practical audience than the elaborately stratified social layers of Berlin, Munich, and Vienna. At the same time, the Jews of Hamburg were carefully circumspect about their involvement in public life. A Jewish merchant or professor could move only so far within German social circles, although Hamburg’s Protestant burghers were more accommodating than most. Both Aby Warburg and Max Warburg belonged to the exclusive Patriotic Society, the point of reference for most of the city’s philanthropic efforts, but their father, Moritz, advised Max against both a military career (in a letter of marvelous brevity: “My dearest Max, meschugge, Your loving father”) and, later, against running for the city Senate (warning that he would never be considered an equal).