 1927 Lecture series in Berlin; Hans Reichenbach and André Weil are in the audience, as is Brouwer’s later assistant Hans Freudenthal. The newspaper Berliner Tageblatt proposes a public debate between Brouwer and Hilbert, to be held in its pages, but for some reason this is not realised. Neither does Brouwer complete the book he is invited to write by the German publisher Walter de Gruyter. The lectures and an incomplete book are published posthumously (Brouwer, 1992).