 1907 Obtains doctor title with dissertation On the Foundations of Mathematics, under supervision of Korteweg at the University of Amsterdam. (The original Dutch title of the dissertation was ‘Over de Grondslagen der Wiskunde’. The present entry will for the most part refer to works cited by using the titles of English translations, with the bibliography providing information about the original publications.) It marks the beginning of his intuitionistic reconstruction of mathematics. Later that year, Brouwer’s wife graduates and becomes a pharmacist. All his life, Brouwer did the bookkeeping for her and filled out the tax forms, and sometimes he assisted behind the counter.