“Right Reason” of Calendar : Focusing on the Explanation of Calendar Notes in Rekirin-Mondo-shu

In pre-modern Japan, calendar cycles regulated people’s activities. In the Heian Period, the Onmyoryo 陰陽寮, one of the government offices, centrally managed information regarding the calendar. As the centuries passed, various people became involved with creation of calendars, and then various information about calendar began to coexist. What kind of knowledge about calendars was believed to be legitimate? In this paper, I will investigate what kind of knowledge was regarded as “right reason 正理” in Rekirin-Mondo-shu 暦林問答集. Rekirin-Mondo-shu is a manual of calendar notes compiled in the Muromachi Period. Kamo no Akikata 賀茂在方, the compiler of Rekirin-Mondo-shu, was the head of Kamo family, who was appointed to create calendars by statesmen. He was proud of himself as a legitimate inheritor of rekido (暦道, the way of calendar) and criticized “heterodox” theories about calendars, such as those of Hoki-Naiden 簠簋内伝. Hoki-Naiden, an unofficial publication, explained calendar cycles by relying on a myth of humanized divinities. In contrast, Akikata’s comments on calendar notes depended on Yin-Yang wu-xing陰陽五行 theory and excluded the elements of humanized divinities, the morality of Confucianism and the Mandate of Heaven theory, even though they were closely combined with Yin-Yang wu-xing theory. Based on the idea that the world had been created and was continuing to exist by mathematical order of Yin-Yang wu-xing, he only accepted the mathematical part of Yin-Yang wu-xing theory as “right reason”.論文/Article