  After Findlay, Łukasiewicz was the greatest single influence on Prior’s development as a logician. Prior’s 1952 review article ‘Łukasiewicz’s Symbolic Logic’ was one of his first papers to make extensive use of symbolism. He there discussed Łukasiewicz’s book Aristotle’s Syllogistic From the Standpoint of Modern Formal Logic (published in 1951) and two articles, ‘The Shortest Axiom of the Implicational Calculus of Propositions’ and ‘On Variable Functions of Propositional Arguments’. The first of these articles stimulated Prior’s interest in economical bases for propositional and pure implicational logics (initially aroused by his study of Peirce) and the opening chapters of Formal Logic drew heavily on Łukasiewicz’s work in this area.