On Four Letters from Ogyū Sorai to Nakane Genkei (Study of the History of Mathematics 2020)

"Study of the History of Mathematics 2020". February 1-3, 2021. edited by Naoki Osada. The papers presented in this volume of RIMS Kôkyûroku Bessatsu are in final form and refereed.Four letters from Confucian Ogyū Sorai (1666-1728) to calendrical calculator Nakane Genkei (1662-1733) have been preserved in the Kansai University Library. In each of these letters, the date and month are only written, but not the year. Although it is not clear when the two met, it is likely that the letters were written between the 10th and 12th year of Kyōhō period (1725-1727). The main content of the letter is related to the request for a preface to Genkei's work, the Kowa-tsūreki (the Japanese Emperor's Almanac) and the Chinese literature, the Jun shi that Genkei planned to publish. The letter also mentions that the two had a disagreement over the evaluation of the Gakuritsu zensho (the Complete Works of Chinese classical Music and Calendrer) written by Zhū zǎi yù (1536 - 1611), which was introduced to Japan from China in July of 10th year of Kyōhō period (1725). In this paper, we will first introduce the contents of the letter, converted into modern printing, as well as the process of writing the preface for the two books and the conflicts between the two sides regarding the value of discovered by Zhū zǎi yù