 Logic and the Basis of Ethics contained no symbolism, and Prior’s phrase ‘the logic of ethics’ was little more than a battle cry. The few technical concepts that he used all related to syllogistic logic. It was not until 1952 that Prior began publishing papers in symbolic logic—four of them, suddenly, in the same year. At the unusually late age of 38 Prior had become a formal logician. He wrote these papers while completing the manuscript of what was intended to be his second postwar book, The Craft of Formal Logic. This began life in 1949 as a Dictionary of Formal Logic, but, at the advice of the Clarendon Press, Prior soon switched to a more orthodox format.