Elena Kagan's senior thesis at Princeton University, recounting the history of socialist politics in New York City, cited the theories of an influential German Marxist who notoriously switched allegiances to Nazism after Adolf Hitler attained power. Werner Sombart was widely recognized as an academic proponent of Marxism and was once praised by Karl Marx's colleague Friedrich Engels as the only German professor who understood Marx's Das Kapital. During World War I, however, Sombart endorsed Germany's "heroic" war against the "capitalist spirit" represented by England. In 1934, Sombart published Deutscher Sozialismus, which advocated the "total ordering of life" as an expression...