Satō Tetsuei, who researched a great many of the works of Zhiyi 智顗 (538–597), drew attention to how Zhiyi seldom cites the Vimalakīrti Sūtra in his Cidi chan men 次第禅門, a work based on his lectures from his younger years, yet in the “Three Great Tiantai Works” (天台三大部) that comprise records of his lectures late in life, the number of such citations increases. Satō points out that Zhiyi’s focus on writing a commentary on the Vimalakīrti Sūtra was, in fact, due to an increased interest in the said sūtra. Of the approximately 110 identifiable citations of the Vimalakīrti Sūtra in the Fahua xuanyi 法華玄義, it is clear that from among all fourteen chapters, the majority of them are from the “Observing Beings 観衆生品,” “Buddha Realms 仏国品,” and “Buddha’s Path 仏道品” chapters. Another observed feature is that a number of citations relate to the theories of other teachers in the Fahua xuanyi. This is a result of the Vimalakīrti Sūtra having been constantly treated as an important scripture in the development of doxography in China. Moreover, Zhiyi had a need to clarify the temporal relationship between the Vimalakīrti Sūtra and other scriptures, in particular the sermons of the Prajñāpāramitā-sūtra, in order to position the Vimalakīrti Sūtra in the fifth time period, hence the increased reliance on teaching classifications.
