称徳天皇の「仏教と王権」 : 八世紀の「法王」観と聖徳太子信仰の特質

抄録

The aim of this article is to examine how Empress Shotoku (Shotoku Tenno 称徳天皇), who had taken the Buddhist tonsure, understood the relationship between Buddhism and kingship, in order to shed light on imperial succession in Japan during the eighth century. Empress Shotoku was of the opinion that the most important issue concerning her successor was that the Buddhist tradition be carried on, and thought that the ideal succession should be based on the joint monarchy carried on between Empress Suiko (Suiko Tenno 推古天皇) and Crown Prince Shotoku (Shotoku Taishi 聖徳太子), the ruler of the Buddhist faith (hoo 法王). So the Empress finally gave up her determined effort to establish a line of succession from the offspring of Crown Prince Kusakabe (Kusakabe-no-Oji 草壁皇子) and instead appointed the monk Dokyo 道鏡 to be her successor. From these facts, the author makes the following points. First, the Buddhist papacy that was given to Dokyo was thought by the Empress to signify the type of kingship determined by Buddhist law as outlined in the Suvarnaprabhasa Sutra (金光明最勝王経), a scripture that was always placed at her right hand. Secondly, the status of her successor would be granted by "heaven" (ten 天) to a person who was worthy of "all the holy gods of the heavens and earth". She also perceived that she had the authority from her father Shomu 聖武 to choose anyone with such worth to be her successor, even if he or she was a slave. It was in this manner that the Empress determined Dokyo to be heaven's choice to succeed her as ruler of the faith. The author also argues that in order to legitimate her choice of a holy monk not of royal blood to succeed her, she cited the inter-pretation of Prince Shotoku's authority that had become popular in the eighth Century. This explanation stated that Prince Shotoku had not been chosen successor because he was of royal blood, but rather because he was the reincarnation of the holy and learned Chinese Buddhist monk, Huisi 慧思. Of course, the Empress' plan was thwarted by a divine message from the Usa 宇佐 Shrine, but the her idea that the Japanese emperor be a Buddhist monk had after her death much influence on Japanese kingship throughout the latter half of the eighth century.