The first recorded initiative to reform the Western ecclesiatical calendar since its creation in antiquity arose at the Avignonese court of Pope Clement VI (1342–1352), who in 1344/45 solicited the advice of expert astronomers in an effort to fix the computation of Easter. Although ultimately unsuccessful, Clement’s plan provides a noteworthy example of scientific patronage at the papal curia, whose background has yet to be explored in sufficient detail. The present article offers a comprehensive survey of this project and its genesis, which will deal with both the various protagonists involved, the specifics under discussions, the reasons the reform failed to come about, and the historical significance of the efforts made. Particular attention will be paid to the possible influence of Hebrew and Greek expertise on the papal reform plan, here represented by the Jewish astronomer Levi ben Gerson and the Byzantine cleric Barlaam of Seminara.
