   It is important for understanding Leśniewski’s development and his attitude to logical systems as endowed with meaning from the start, and not meaningless formal games, to know that he developed in his systems chronologically in the reverse order from their order of logical priority. Logically, protothetic precedes ontology, and ontology precedes mereology, but he worked them out starting from mereology and working through ontology to finish with protothetic. Becoming frustrated with the inexactnesses and foibles of natural language as a medium for working, in 1920 Leśniewski let himself be persuaded by Leon Chwistek that it would be advantageous to overcome his distaste for symbolism and formulate his logical thoughts using symbols. Mereology having been rather well formulated already in 1916, the transition to symbolism was straightforward there. The fact that axiomatization came first, and symbolization of the already axiomatized theory followed subsequently, gave Leśniewski a strong reason to dissociate the use of formal methods from formalism, according to which formulas are without interpretation. Leśniewski’s formulas had an intended interpretation from the start.