of PhD dissertations at Harvard for three decades, especially in the fields of social, women's, and immigration history. He commented in 1922, "From reading history in textbooks one would think half of our population made only a negligible contribution to history." He promoted social history by co-editing the 13-volume History of American Life (1928–1943) series with Dixon Ryan Fox. These thick volumes, written by leading young scholars, mostly avoid politics, individuals, and constitutional issues. They instead focus on such topics as society, demographics, economic, housing, fashion, sports, education, and cultural life. In "Tides of American Politics," a provocative essay in the Yale Review in 1939, he presented his cyclical view of history which identified irregular oscillations between liberal and conservative national moods, but it attracted few historians apart from his son. Schlesinger introduced the idea of polling historians to rank presidential greatness, which attracted much attention. In an essay on "The Significance of Jacksonian Democracy" (in New Viewpoints in American History (1922)), Schlesinger drew attention to the fact that "while democracy was working out its destiny in the forests of the Mississippi Valley, the men left behind in the eastern cities were engaging in a struggle to establish conditions of equality and social well-being adapted to their special circumstances." As a historian of the rise of the city in American life, he argued that for a full understanding of the Jacksonian democratic movement: "It is necessary to consider the changed circumstances of life of the common man in the new industrial centers of the East since the opening years of the nineteenth century." That was a challenge to the frontier thesis of his Harvard colleague Frederick Jackson Turner. In Schlesinger's essay, the common man of the Mississippi Valley and the common man of eastern industrialism stood uneasily side by side. Schlesinger characterized prejudice against Catholics as "the deepest bias in the history of the American people". Schlesinger and his students took a group approach to history, sharply downplaying the role of individuals. Groups were defined by ethnicity (Germans, Irish, Jews, Italians, Hispanics, etc.) or by class (working class, middle class). Their model was that the urban environment, including the interaction with other groups, shaped their history and group outlook in deterministic fashion. Works 1917 The Colonial Merchants and the American Revolution, 1763–1776 online 1922 New Viewpoints in American History, historiographical essays online 1925 Political and Social Growth of the American