 During the heyday of the Warsaw School, 1920–1939, Łukasiewicz played a key role in educating the next generation of logical researchers and inspiring them with methods, results and problems. Even ideas he tossed off as exercises have changed logic, for example a 1929 suggestion to formalize the informal procedure of proof from assumptions led to Stanisław Jaśkowski’s 1934 system of natural deduction, in essentials the way logic is mainly taught to students today. The war irrevocably interrupted their work. Several of Łukasiewicz’s best students were Jewish, and were killed in Nazi death camps. In his exile from Poland after 1944, Łukasiewicz had scant opportunity to continue this pedagogical work, holding a research position in a non-teaching institution in a country with no logical tradition. His interactions with contemporaries were much more sparse, and those chiefly through correspondence. The one notable logician who interacted with Łukasiewicz at this time and whose work intersects with his in both interests (time, modality, many-valuedness) and attitudes (the importance of logic for philosophy) is Arthur Prior, who was the only major logician to adopt Polish notation, and who also expended more effort than anyone in the attempt to find a plausible interpretation for the system Ł. It is also fair to say that of the major figures among the Warsaw logicians, Łukasiewicz has received the least attention from commentators and historians. There are relatively fewer monographs and papers on Łukasiewicz than on other major figures of the Lwów–Warsaw School.