<論説>室町期における大内氏の妙見信仰と祖先伝説

Abstract

本稿では、道教史、美術史など多様な分野での妙見信仰の研究成果を踏まえながら、大内氏の妙見信仰と祖先伝説の関係を論ずる。大内氏の妙見信仰は南北朝中期までは一族の私的な信仰に留まっていたが、南北朝後期に妙見は大内氏全体を代表する氏神となった。室町期になると、大内氏は祖先伝説の体系化に力を入れるようになり、琳聖太子が祖神とされる段階を経て、次第に祖先伝説の主要な構成要素が出来上がっていった。大内氏は、道教の真武神的な妙見を象徴する幼名(亀童丸) を与えることで嫡子を琳聖太子になぞらえ、祖先伝説を家督争奪戦という現実の危機を回避するために役立てた。最後に、政弘の代で氏神(妙見) が守護神として始祖(琳聖太子) に結び付けられた上、興隆寺を中心とする妙見信仰の由緒が語られ、祖先伝説が体系化された。ここに、大内氏の妙見信仰は、領国支配イデオロギーの中核を成す、スケールの大きな信仰に変容したのである。

In recent years increasing attention has been paid to Rinsho Taishi 琳聖太子 (Crown Prince Rinsho), who was seen as the ancestor of the Ouchi clan, and much progress in research on the legend of the Ouchi ancestor has been made. Growing out of this trend is a clear awareness of the importance of the Ouchi clan in the Muromachi state in terms of its role in both the system of the Muromachi bakufu and in foreign relations. However, the results of recent studies of faith in Myoken 妙見 have not been sufficiently applied to the state of research into the Ouchi clan. While Myoken, the tutelary deity of the Ouchi, along with Rinsho Taishi, forms the core of the ancestral legend of the Ouchi, many points regarding its fundamental character remain unclear. The Ouchi frequently conducted Myoken rituals to pray for the peace of their lands, and Nigatsu'e (Second Month Festival)of Koryuji 興隆寺 had particular political significance as the retainers and people of the land were required to pledge loyalty to the Ouchi. I understand Myoken faith of the Ouchi as playing the role of the ruling ideology in these lands and an important element in the study of the Ouchi clan. In this article, I argue four issues regarding the ancestral legend and the Ouchi faith in Myoken during the Muromachi period based of the results of research on Myoken faith in terms of various fields, such as the history of Daoism, art, medieval history, and folklore. The first issue is the origin of the Ouchi faith in Myoken. The relationship between Myoken and the Ouchi-no-suke 大内介 family, the forerunners of the Ouchi clan, can be traced in the historical record with certainty back to the early Nanbokucho period, and there is a great possibility that it goes back to the Kamakura period. On the basis of analogous warrior groups that also worshipped "stars" during the Kamakura period, and we can surmise that it was necessary for the Ouchi-no-suke family to have Myoken as a tutelary deity in order to maintain a consciousness of their legitimacy. Nevertheless, this faith in Myoken was an internal matter conducted within the Ouchi-no-suke family alone until the middle of the Nanbokucho period. The second issue is how Myoken, the tutelary deity of the Ouchi clan, was linked to the clan ancestor, Rinsho Taishi. During the time of Morimi 盛見, Myoken was only one of several gods worshipped by the Ouchi, moreover Rinsho Taishi had the character of ancestral deity, kami, of the Ouchi clan. Before there could be a linkage of Myoken with Rinsho Taishi, it was necessary that Rinsho Taishi go through the stage of becoming a kami himself. In the ancestral legend prior to the time of Norihiro 教弘, the tutelary deity Myoken had not been linked with Rinsho Taishi, the clan ancestor. It can be surmised that this state is closely related to the fact that Koryuji had yet to become the core of the ruling ideology of the territory prior to the time of Norihiro. The third issue is the fact that the image of Myoken held by the Ouchi was that of an avatar of a Buddhist deity in the form of a youth that was derived from the Daoist deity Zhenwu 真武 (Jp. Shinbushin). The heir to Ouchi clan leadership was invariably called Kidomaru 亀童丸 as a child. This childhood name was derived from the turtle, which was a symbol of Myoken, and indicated that he was under the protection of Myoken. By giving a childhood name to the heir of the Ouchi clan that symbolized a Zhenwu-like Myoken, the heir was being likened to Rinsho Taishi. It can be said that Myoken would not only protect the heir from suffering a painful death, but would also confer legitimacy on the heir alone, and thus provide the authority that would prevent strife within the clan over its leadership. The fourth issue is the fact that consciousness of Myoken's presence within the ancestral legend became clear in the latter half of the 15th century in the time of Masahiro 政弘. It was at this stage that Myoken became the tutelary deity of Rinsho Taishi in the ancestral legend and the two were linked. Then, with the recounting of the origins of Myoken faith centered on Koryuji, the ancestral legend was elaborated and developed into its most detailed form. The account of origins of the Ouchi clan that was written in Bunmei 18 (1486) was an important landmark in the ancestral legend of the Ouchi clan. Ouchi Masahiro not only made Myoken the tutelary deity of Rinsho Taishi but also transformed it into a deity whose scale was large enough to serve as the core of the ruling ideology of the territory. I have argued in this article that the Ouchi clan used a Zhenwu-like image in constructing a systematic ancestral legend that provided the religious order for the rule of their territory.