空海（774-835）的十住心論：從《大日經》到《秘藏寶鑰》

空海為日本真言宗創始人。空海的重要理論除了即身成佛之外，另一個代表觀念為其「十住心論」，闡釋此概念的論著為《十住心論》（全名為《秘密曼荼羅十住心論》）以及《秘藏寶鑰》。空海於後期將十卷《十住心論》濃縮為三卷《秘藏寶鑰》之精要版本。然而不只是卷數之長短不同，成立於後的《秘藏寶鑰》還強調了自身與《大日經》的關聯性，透過問答引用《大日經》文句，《秘藏寶鑰》表達了自身作為「論」的正當性與必要性。本文將闡釋《秘藏寶鑰》中「十住心論」的涵義，剖析空海如何詮釋經文，以及再創造之解經方法，例如援引《華嚴經》之思想乃為空海所添加，此外在成佛論的概念上顯見真言宗與天台宗交涉並互相影響之軌跡，最後在第十住心整合兩界曼陀羅，則為真言宗提昇修證地位的優越性。意即空海「十住心論」並非根據《大日經》以及《大日經疏》進行注釋，而是他自己的創見。而兩者之間的歧異所在，顯露空海的密教知識論，以及空海的撰述動機。本文藉此探討《秘藏寶鑰》如何能發揮佛教文類之一「論典」（śāstra）的角色，和「論典」在東亞變化之樣貌。

關鍵字

空海；真言宗；大日經；十住心論；秘藏寶鑰

並列摘要

Kūkai was the founder of the Shingon sect in Japan. In addition to the theory of "enlightenment in this very body" (Jp. sokushinjōbutsu), Kūkai's most important concept was his "Theory of the Ten Abiding Minds", explained in the Jūjūshinron [Ten Abiding Minds Treatise] and the Hizōhōyaku [The Secret Treasure Key]. In later years, Kūkai condensed the ten volumes of the Ten Abiding Minds into three volumes of the Hizōhōyaku. However, in addition to the difference in the length of the volumes, the later-established Hizōhōyaku also emphasises its connection with the Mahāvairocana Sūtra. By quoting from the Mahāvairocana Sūtra in the questions and answers, the Hizōhōyaku expresses the appropriateness and necessity of being a "treatise" (śāstra). In this paper, we will explain the meaning of the Ten Abiding Minds Theory in the Hizōhōyaku, analyse how Kūkai interpreted the sutra, how he interpreted the Avataṃsaka Sūtra, his strategy for arguing against the Tendai school, and his method of interpretation. Taken together, this means that Kūkai's theory of the Ten Abiding Minds was not based on the Mahāvairocana Sūtra, but rather was his creative idea. These discrepancies reveal Kūkai's theory of tantric knowledge and his motivation for writing it. This article then explores how this treatise fulfils the role of a śāstra, one of the genres of Buddhist texts, in the cultural context of East Asia.