Kukai (774-835) is the founder of the Shingon sect in Japan. The most well-known theory of Kukai's is probably that of “becoming a Buddha in this life.” In addition, another representative concept is his "Ten Abiding Mind Theory"; the major works which explain this concept are his "Treatise on the Ten Abiding Minds" Theory" (Jp. Jūjūshinron 十住心論 , full name: "Treatise on the Secret Mandala of Ten Abiding Mind", Jp. Himitsumandara -jūjūshinron 秘密曼荼羅十住心論 ) and the "Secret Treasure Key" (Jp. Hizōhōyaku 秘藏寶鑰 ). In a later period, Kukai condensed the ten fascicles of "Treatise on the Ten Abiding Minds" into the three-fascicle "Secret Treasure Key". However, not only are the lengths of the volumes different, but the "Secret Treasure Key" written later also emphasises the relevance between the Mahavairocana Sutra and itself. Through questions and answers, there are ample quotations from the Mahavairocana Sutra; in this way, the "Secret Treasure Key '' attempts to testify its legitimacy and necessity of being a "śāstra" (ie. a standard Buddhist treatise).
This article will explain the theoretical connotations of "Theory of Ten Abiding Minds" in "The Secret Treasure Key", as well as analyse how Kukai interpreted the scriptures, and how he recreated the method of interpreting scriptures. In other words, this means that Kukai's "Theory of Ten Abiding Minds" is not entirely based on the Mahavairocana Sutra or the Chinese "Commentary to the Mahavairocana Sutra as he claims in his works, but much more out of his own originality and reinterpretation. The doctrinal difference between these scriptures reveals Kukai's epistemology of Esoteric Buddhism and Kukai's motivation for inventing these theories.
