 In March 1933, Gödel received a letter from Paul Finsler, from Zürich, who suggested that he had already earlier (in Finsler 1926) done closely related work but with a more general relevance. Gödel replied that Finsler’s system was not really defined at all. In his heated response, Finsler claimed that it was not necessary to be able to study a system for it to be sharply defined, and that there was no difference in principle between his ideas and Gödel’s. In retrospect, it is quite clear that the approaches of Finsler and Gödel were very different: for Gödel’s work, the notion of formalized system was essential, whereas Finsler rejected the very notion as artificially restrictive. In fact, it is far from clear that Finsler’s ideas make any sense—whatever vague analogies there may be between them and Gödel’s proof.