 Interestingly, Glivenko mentions in his paper that “It is Mr. A. Heyting who first made me see the appropriateness of the two axioms C and D in the Brouwerian logic” (Mancosu 1998: 304–305n.3). The two had come into correspondence when, upon the publication of Glivenko 1928, Heyting sent Glivenko a letter (Troelstra 1990: 11). Kolmogorov in 1925 had explicitly rejected Ex Falso for having no “intuitive foundation”. From Glivenko’s letter to Heyting of October 13, 1928, we know that Glivenko was aware of this (Troelstra 1990: 12). In his paper, however, which he finished later, he does not mention Kolmogorov at all. Instead, he makes the remark on Heyting just quoted and then justifies D by saying that it is a consequence of the principle \((p \vee \neg q) \rightarrow (q \rightarrow p)\), the admissibility of which he considers “quite  evident”.[23]  From a Brouwerian point of view, however, the principle is as objectionable as Ex  Falso.[24]  It is worth noting that, when Heyting gave his justification for Ex Falso in Heyting 1956: 102, he did not appeal to the principle Glivenko had used (nor did Kolmogorov in 1932). From Glivenko’s letter of October 18, 1928, one gets the impression that this principle had not been the argument Heyting had actually given to convince him: