The document discusses the professionalization of history as an academic discipline in the 19th century, led by historians like Leopold von Ranke who emphasized researching history "as it really was" through rigorous analysis of primary sources. It introduces several influential historicist thinkers like Hegel, Comte, Marx, and Nietzsche, noting how Marx combined historicism with materialism and class struggle to develop his theories of history unfolding through modes of production. The document cautions that meta-historical theories seeking to explain all of history, while popularized by these thinkers, could enable totalitarian ideologies like those of the Nazis and fascists if taken to an extreme.