for three months by the German police in the notorious Amersfoort police detention camp, and returned to writing and teaching. In 2011 Jan Romein and his wife were posthumously awarded the title "Righteous among the Nations" by Yad Vashem in Jerusalem, for offering a hiding place to two persecuted Jewish fellow-citizens during the German occupation. In 1937, he published an essay on technology called "The dialectics of progress" (in Dutch: "De dialectiek van de vooruitgang") in which he describes a phenomenon called the "Law of the handicap of a head start" ("Wet van de remmende voorsprong"), as part of the series "The unfinished past" (in Dutch: "Het onvoltooid verleden"). This article was also published in German as "Dialektik des Fortschritts" in: Mass und Wert. Zweimonatsschrift für freie deutsche Kultur (eds. Thomas Mann and Konrad Falke), vol. 2 (Zurich, Switzerland, 1939). In 1946, Annie Romein received a copy of Anne Frank's diary which she tried to have published. When she was unsuccessful, she gave the diary to her husband, who wrote the first article about the diary and its writer, for the newspaper Het Parool. Interest raised by his article led to the diary being published the following year. Romein was interested in the (auto)biographical approach to history. During the years of German occupation he wrote a book on this, which was published in 1946 (German translation 1948) and is still regarded as an informative and original contribution to the historiography of the genre. Also in 1946, he introduced the theory of history as a subject in the academic curriculum. Soon after the beginning of the Cold War his marxist conceptions, though undogmatic, had placed him in relative isolation, and in 1949 he was denied entry to the United States for an intended speaking engagement at an international scholarly conference in Princeton of which he was one of the initiators. Instead, he was welcomed as a guest professor in the young republic of Indonesia during the 1951–1952 academic year. He devoted the latter part of his life to writing a history of Europe during the 25-year period from 1889 to 1914: The Watershed of Two Eras. Europe in 1900, which was published posthumously in 1967 (English edition 1978). According to various reviewers it "is a highly successful attempt at writing an analysis and synthesis of European history between the years 1890 and the outbreak of the First World War", the decades