 Łukasiewicz’s third signal achievement, along with his investigations of many-valued and propositional logics, is his work in the history of logic. Indeed he can reasonably be considered the father of the modern way of doing the history of logic, which is pursued, to quote the subtitle of his book on Aristotle’s syllogistic, “from the standpoint of modern formal logic.” We saw that his early book on the principle of contradiction in Aristotle was relatively unsuccessful in its own terms, though it demonstrated his ability to go to the heart of the ancient Greek texts.