著者

吉川 真司

出版者

国立歴史民俗博物館

雑誌

国立歴史民俗博物館研究報告 (ISSN:02867400)

巻号頁・発行日

vol.134, pp.7-26[含 英語文要旨], 2007-03

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本稿は、大極殿で行なわれた儀式を素材として、日本古代史の時期区分を論じ、とりわけ四字年号時代(七四九〜七七〇)の時代相を明らかにしようとするものである。第一章では、即位儀・朝賀儀において大極殿前庭に列立された七基の宝幢について再考する。私はかつて、(一)宝幢の基礎部分は常設の美しい構築物であったこと、(二)平城宮には中央区・東区という二つの大極殿院があるが、両区ともに宝幢樹立が認められること、などを論じた。これに対して金子裕之は、吉川説は遺構解釈において重大な過誤を犯しているとし、平城宮中央区大極殿院で宝幢が立てられたこと、東区大極殿院で宝幢基礎部分が常設されたこと、そのいずれをも否定する。また西本昌弘は、中央区大極殿院の宝幢遺構は称徳朝の西宮に伴うものとする新たな解釈を提示した。これらの反論を逐一吟味したところ、ともに遺構解釈のポイントと言うべき、同位置で何度も立て替えがなされる宝幢の特異性が十分配慮されておらず、私見を改める必要はないという結論に達した。さらに宝幢と一連の荘厳施設である衛府儀仗については、その意匠が一新されたのは天平宝字二年のことと考えられ、藤原仲麻呂政権の唐風化政策との関わりから理解することができるのであって、金子の強調する桓武朝の画期性はさほど重視できない。第二章では、これまで検討が手薄であった、大極殿での仏教儀礼について検討する。平安時代、大極殿法会の中心となったのは御斎会であり、それは年頭における最勝王経講讃の儀として、称徳朝に始修されたと考えられる。御斎会の意義は、その空間構造から理解されねばならない。いくつかの復原案を取捨しつつ考察したところ、(一)天皇御座の高御座が盧舎那仏の仏座に用いられ、(二)高御座を置く方形の壇が須弥壇とされ、(三)大極殿全体が「講堂」と呼ばれる仏堂に変じ、さらに(四)朝堂院が僧房・供養所などに利用される、といった特徴が確認できた。すなわち、講堂・食堂・僧房という主要施設をもつ仮設寺院が、毎年正月の一週間、古代王宮の中枢部に出現した訳であり、法会の連動性から考えて、この仮設寺院は諸国国分寺を統括する「総国分寺」的な役割を果たしていたと評価することができる。画期的な大極殿利用法と言えようが、それは称徳朝の「仏教政治」下の異常事態ではない。平安時代にそのまま年中行事として定着することからすれば、仏教を一つの原動力とする「文明化」の到達点の表現であったと考えられる。一・二章における大極殿儀式の検討は、主たる素材と論点を全く異にしているが、時期区分論については同じ方向性を有している。それは光仁・桓武朝の画期性を強調しすぎることへの異議であり、かつその直前に位置する四字年号時代の再評価である。私見によれば、四字年号時代、特にその頂点とも言える称徳朝は「奈良時代の袋小路」ではなく、きわめて先鋭的・躍動的・創造的な時代であった。王権への権力集中、国家財政の富裕化、中国文明への没入などを伴いつつ、それまでの「文明化」過程が総括され、平安時代の政治・文化・宗教の直接の基盤がこの時期に生み出された。光仁・桓武朝も確かに小画期と認められようが、余りにそればかりを強調すると、桓武の宣揚した「王朝交替の物語」に取り込まれる結果となりかねないのである。This paper examines the classification of periods in ancient Japanese history based on ceremonies performed at the Daigokuden with the aim of clarifying the periods that existed between 749 and 770 when four-character period names were adopted in accordance with the Chinese system.The first section reinvestigates the seven decorative banners (hodo) that stood in a row in front of the Daigokuden when accession rituals and the Choga ceremony on New Year's Day were held. The author previously argued that 1) the foundations of the banners were beautiful permanent structures; and 2) although there were two Daigokuden-in in Heijo Palace ― one in the central precinct and one in the eastern precinct ― it is accepted that banners stood in both areas. Hiroyuki Kaneko has attacked this argument saying that it commits a serious error with regard to the interpretation of the ancient remains. He rejects that banners were erected at the Daigokuden-in in the central precinct of Heijo Palace and also rejects that the foundations of the banners at the Daigokuden-in in the eastern precinct were permanent structures. Masahiro Nishimoto had advanced a new interpretation that suggests that the remains of the banners at the Daigokuden-in in the central precinct are associated with the Nishinomiya during the reign of Empress Shotoku. Following a detailed examination of these criticisms, the author has reached the conclusion that there his no need to amend his opinion because they take insufficient account of the specific properties of the banners that would have been reerected time and time again on the same site. Thus, the argument rests on the interpretation of the ancient remains. Furthermore, with respect to the banners and the imperial guard units, it is believed that their design was revamped in the second year of the Tempyo Hoji era and that they can be understood in the context of their association with the Fujiwara no Nakamaro administration's policies for Chinese acculturation. Consequently, not much credibility can be given to the importance of the Kammu era attached by Kaneko.The second section examines Buddhist ceremonies held at the Daigokuden, a subject that has received scant attention to date. During the Heian period, Gosai-e ceremonies were the main Buddhist services held at Daigokuden. It is believed that it was during the reign of Empress Shotoku that they were first held at the start of the year for reading the Saisho Okyo sutra. The significance of the Gosai-e must be understood in terms of its spatial structure. The author was able to confirm the following features by looking at several plans for its restoration: 1) The imperial throne was used as the throne for the Vairocana Buddha; 2) the square platform on which the imperial throne was placed was regarded as a shumidan ― a platform on which a Buddha was seated; 3) the entire Daigokuden became a Buddhist hall called a "kodo"; and 4) the Chodo-in was used as living quarters for Buddhist monks and for memorial services. That is to say, for one week every New Year a temporary temple containing the important facilities of a hall, dining hall and living quarters appeared in the central area of imperial palaces during the ancient period. Viewed from the perspective of Buddhist services, we may regard this temporary temple as serving as the main Kokubun-ji temple for the Kokubun-ji temples located in each province. Although one would like to call this an innovative method of using the Daigokuden, it was not out of the usual within the "Buddhist politics" of the reign of Empress Shotoku. Viewed from the perspective of these same services becoming established as a yearly event during the Heian period, it represented an end point of "civilization" for which Buddhism was one of the driving forces.Even though the main materials and points of contention in the examination of Daigokuden ceremonies in sections one and two are completely different, they point in the same direction in terms of the debate on the classification of periods. They dispute the excessive emphasis placed on the epochal qualities of the Konin and Kammu eras, and, moreover, re-evaluate the period of four-character period names that comes immediately before. The author contends that this period, especially its zenith at the time of the reign of Empress Shotoku, was not the "cul-de-sac of the Nara period," but instead was a radical, active and creative period. It was during this period that along with the concentration of authority in the imperial throne, the wealth of state finances and the preoccupation with Chinese civilization that brought together the process of "civilization" up until that time created an immediate foundation for the politics, culture and religions of the Heian period. The Konin and Kammu eras should also be acknowledged as eras of some importance, but if we stress only these eras we run the risk of becoming caught up in the "Tale of the Changing Imperial Dynasties" promoted by Emperor Kammu.