This study attempts to identify the reasons why Yukai, a scholar-monk of the Shingon School in the Muromachi era, presumed that the Zo-mondo was not Kukai's work, despite the fact that it had generally been believed to be his work until the early Kamakura era. Yukai's conclusion has been accepted in academia. Therefore, in order to confirm the foundation of Yukai's supposition, this study examined quotations of the Zo-mondo in Yukai's works. The findings are that the Zo-mondo contradicts Kukai's Sokushin jobutsu-gi and that the Xindiguan jing, which had not yet entered Japan in Kukai's times, is excerpted in the Zo-mondo.

In this article, I examine how Yukai understood the concept of bonno-soku-bodai (klesa or afflictions are the same as bodhi or enlightenment). Yukai (1345-1416) was a Muromachi era scholar-monk of the Shingon School. In his first work, the Hokyosho, he criticized the heretical Tachikawa Sect emphasizing their misunderstanding of bonno-soku-bodai. In his treatise, the bonno-soku-bodai-gi, he used Kukai's classification from The Ten Stages of the Development of Mind (Jujushinron) to analyze and rank bonno-soku-bodai in ten stages. He insisted that each stage be considered carefully and that bonno-soku-bodai be accurately understood according to the Shingon School's teachings. Yukai's fundamental interpretation of bonno-soku-bodai was based on Kukai's philosophy and then further developed.