Clavius in Nanban cosmology : Astronomical data in Pedro Gomez's Compendium catholicae veritatis and its sources

Abstract

In 1593-94, a Spanish Jesuit Pedro Gomez (1533-1600) completed his tripartite textbook for use by students preparing for the priesthood at Jesuit colleges in Japan. Its first part, De sphaera (On the Sphere), is well known as the first full-scale presentation of Western cosmology in Japan. However, it has been rarely noted that its third part, Compendium catholicae veritatis (Compendium of Catholic Belief), which treats theology, also contains such technical astronomical data as the dimension of the heavens. Comparison of Compendium's data with those seen in astronomy books in contemporary Europe has shown that some of the numerical values in fact correspond to those of a famous Jesuit mathematician Christoph Clavius (1537-1612), whose influence on De sphaera has already been indicated. This paper, while providing a modern Japanese translation of the related chapter in Compendium, first investigates the derivation of the data and, second, examines whether it influenced similar data seen in Kenkon Bensetsu (A Discussion on the Heavens and the Earth with Critical Commentaries) and its variant copy Tenmon Biyo (Compendium for Astronomy), both composed in the mid 17th century and attributed to the apostate Portuguese Chuan Sawano (Christovao Ferreira, ca.1580-1650).