 While not in itself a success, the book shows Łukasiewicz on the threshold of his later logical breakthroughs. It was read in 1911 by the young Leśniewski, who sought against Łukasiewicz to prove OPC, and who first introduced himself in 1912 on Łukasiewicz’s doorstep with the words, “I am Leśniewski, and I have come to show you the proofs of an article I have written against you.” The book also contains a brief discussion of Russell’s Paradox, and it was reading this that inspired Leśniewski to become a logician, intent on providing a paradox-free logical foundation for mathematics. The book promoted further discussion in Lwów: Kotarbiński wrote in defense of Aristotle’s idea, discussed by Łukasiewicz, that a statement about future contingent events may lack a truth-value before the event and only gain one afterwards, while Leśniewski wrote in opposition to this and brought Kotarbiński round to his own view (which agreed with earlier views of Twardowski and later ones of Tarski) that truth is timeless, or as Leśniewski expressed it, both eternal and sempiternal. Łukasiewicz was soon to side with the earlier Kotarbiński, and in so doing to make his most famous discovery, that of many-valued logic.