   Throughout the 1920s, Leśniewski and his students worked hard to improve the logical systems by finding single axioms, shorter axioms, trying out new primitives, and generally seeking logical perfection. The work, and Leśniewski’s involvement in teaching, were so intense that for several years he published nothing. As this became something of an embarrassment, since his results were being quoted without being in print, he resolved to postpone a fully systematic exposition and present instead a more autobiographical account of how the systems arose and were improved. This took the form of two series of articles from 1927–31. One series, ‘O podstawach matematyki’ [‘On the Foundations of Mathematics’] appeared in the premier Polish philosophy journal Przegląd Filozoficzny, and, eschewing mathematical symbolism, was dedicated to an up-to-date exposition of Mereology. The other series, ‘Grundzüge eines neuen Systems der Grundlagen der Mathematik’ [‘Fundamentals of a New System of the Foundations of Mathematics’] began to appear in 1929 in the mathematical journal Fundamenta Mathematicae, and was dedicated to Protothetic. Its 81 pages and 11 sections ended with the promise ‘Fortsetzung folgt’, ‘Continuation follows’, but it did not, because in the meantime Leśniewski had fallen out with the other editors of the journal over the status of set theory. The article did not get beyond the preliminaries of Protothetic, setting out the history, axioms, and rules (directives) for extending the system, and outlining a number of variants, but not starting the deductions proper. It was not until a new logic journal Collectanea Logica was set up in 1938 that Leśniewski was able to continue. After a 60-page introduction to the continuation, ‘Einleitende Bemerkungen zur Fortsetzung meiner Mitteilung u.d.T. “Grundzüge eines neuen Systems der Grundlagen der Mathematik” ’, summarizing the earlier article and bringing the story up to date, there followed another 83 pages comprising Section 12, and listing twelve definitions and 422 theorems of Protothetic, with skeletal information about how they are derived, expressed in Leśniewski’s own idiosyncratic notation for the connectives and quantifiers. The journal did not appear in print because of the outbreak of the Second World War: the printing plates from which offprints had fortunately been made were destroyed in the bombing of Warsaw in September 1939, by which time Leśniewski was already dead.