Zermelo's letter to Paul Bernays, an answer to Bernays' 70th birthday congratulations, has been included as the last entry of the present collection as it vividly conveys the feeling of loneliness and the fear of falling into oblivion which dominated Zermelo's last years. There are several reasons that contributed to this. Scientifically, his fight against the predominance of finitary approaches in the foundations of mathematics had failed. Even more, he was considered as a researcher of the previous generation unable to play an active part in shaping mathematical logic in the 1930s. According to John W. Dawson in his biography of Kurt Gödel (Dawson 1997, 75), Zermelo's fight was a "reactionary" one.