Preliminary review / Publisher’s description: Otto Blumenthals (1876‒1944) Tagebücher haben es wahrhaftig in sich. In mehr als eineinhalb tausend Tagebucheinträgen von Sonntag 1. Januar 1939 bis Donnerstag 22. April 1943, über vier Jahre und vier Monate also, notiert er akribisch Tag für Tag von morgens bis abends oder nachts alle Ereignisse, die ihm wichtig erscheinen und dokumentiert damit sein eigenes Schicksal, das Schicksal seiner Frau und Familie sowie das vieler Leidensgefährten in der Nazidiktatur, ohne dabei die vielen mutigen Menschen zu vergessen, die immer wieder zu helfen versuchten. Es ist der Leidensweg eines hochgeachteten Mathematikprofessors an der Technischen Universität Aachen durch Anfeindungen und Verleumdungen, Entrechtung, Emigration nach Holland, Ausbürgerung aus Deutschland, Demütigungen ohne Ende bis zur Deportation von Westerbork (Holland) nach Theresienstadt, wo er Ende 1944 stirbt. Otto Blumenthal und seine Frau waren evangelische Christen jüdischer Herkunft, die am 17. Juli 1939 von Aachen in die Niederlande emigrierten, am 11. Januar 1941 ausgebürgert wurden, deren Ausweise ab dem 14. Juli 1941 den J-Stempel trugen, und die ab 3. Mai 1942 den gelben Judenstern tragen mußten. Professor Blumenthal war drei Jahre lang im Ersten Weltkrieg und Träger des EK II, was ihm allerdings nur half, in Theresienstadt und nicht gleich in Auschwitz zu enden. Bereits am 28. Januar 1941 wurde ihm von der Universität Göttingen der Doktor-Titel aberkannt (und posthum am 27. Oktober 2004 wiederverliehen bzw. zurückerstattet). Otto Blumenthal war jedoch bereits am 13. November 1944 in Theresienstadt verstorben, seine Frau Mali schon am 21. Mai 1943 im holländischen NS-Durchgangslager Westerbork. Otto Blumenthals inhaltsreiche, faszinierende, ergreifende Tagebücher wären ohne Dr. Volkmar Felsch wohl nie veröffentlicht worden, und sie wären ohne seine sorgfältige Transkription und ohne seine ebenso akribischen wie umfassenden Recherchen, Erklärungen und Kommentare allenfalls nur halb so verständlich und aufschlußreich, weshalb ihm für seine jahrelange und außerordentlich engagierte Erinnerungsarbeit besonders herzlicher Dank gebührt. Otto Blumenthal hat schon zu Beginn des Zweiten Weltkriegs am 1.9.1939 gesehen und vorausgesehen: “Es ist entsetzlich, und die Folgen werden noch entsetzlicher sein."

This is a very careful edition of the diaries of the German-Jewish mathematician Otto Blumenthal which he wrote in German between 1939 and 1943, partly in Aachen, partly in emigration to the Netherlands. He was in this neighbouring country since August 1939 together with his wife, before they were deported and died in Westerbork (his wife Mali in 1943) and Terezin (he in November 1944). The entries in the diaries are very short and only rarely emotional. But together with elaborate footnotes and additional documents they constitute a breathtaking documentation of the gradually increasing discrimination of Jews under German occupation following May 1940. Blumenthal’s children Ernst and Margret, who were forbidden to complete their studies in Germany in the 1930s, managed to escape to England. Felsch traced the diaries in Northwich in 2003 in the possession of Ernst’s widow. Felsch found there additional documents, in particular letters of the Blumenthals to their children and witness reports about the death of Mali and Otto. The editor embeds the diary into a biography of Blumenthal, which does not aim at his mathematical work. Otto Blumenthal had been known as the first doctoral student of David Hilbert (1898) and as his first biographer (1935), but above all as the long-term managing editor of Mathematische Annalen. His own mathematical work (mainly in function theory) ranked second compared to his organisational activity for the community of mathematicians. He was dismissed in 1933 from his position as professor of mathematics in Aachen (officially for political reasons which led to a 25 percent cut in his pension) and 1938 from the Annalen. Heinrich Behnke who later was to take over as managing editor said already in 1935: “Of course I could not replace Blumenthal. In his willingness to read each and every manuscript (even the corrections) he is simply irreplaceable." (p.45). The diaries are unique in describing the life of an emigrated Jewish mathematician to a country occupied by the Germans during World War II, and the gradual deterioration of the living conditions. When he had to wear the Star of David following April 1942 Blumenthal remarked: “First familiarity with the Star of David which is deliberately ugly and insulting." (30.4.42).The diaries also document, however, much support which the Blumenthal couple received by Dutch colleagues (such as J. A.Schouten, B. van der Pol, J. Burgers, C. A. Biezeno, and Julius Wolff, the latter was also killed by the Germans) and by neighbours, which makes the diaries very moving. Blumenthal and his wife went to Bible sessions of the emigrated German pastor of the Bekennende Kirche Bruno Benfey; they had converted to Protestantism many decades before, which, however, did not matter for the Nazis. The only criticism of the well written and thoroughly researched book is the lack of reference to general and comprehensive literature on the emigration of Jewish mathematicians, which would have allowed making comparisons with the fates of others, also in the Netherlands, of whom several survived in hiding. The Blumenthal project had been started by an initiative of the town of Aachen in 1997, named “Ways against forgetting". It led, in addition to the publication described, also to the erection of a commemorative plaque in front of Blumenthal’s former home.
Reviewer: Reinhard Siegmund-Schultze (Kristiansand)