 1904–1907 Doctoral studies. His mathematical and philosophical notebooks towards his dissertation show strong influence from notably Cantor, Hilbert, Russell, Poincaré, and Couturat. He is aware of the Frege–Hilbert debate, and in that matter sides with Frege. Some remarks betray a form of anti-semitism that, unfortunately, often appeared in language at the time, as codification of a common prejudice; an occasional remark goes further and contrasts Jewish people unfavourably to Germanic ones. No such utterances are known from other periods in his life; compare also the entries for 1934–1935 and 1940–1945 below. There is no meaningful connection between this fleeting anti-semitism and the philosophical views on mathematics, language, and society he set out in his dissertation and developed over the rest of his life. 