[Page 90-91] The turning point in Saichō’s career began with a trip to Tōgoku (Eastern provinces) in 817. … During his travels in Tōgoku, Saichō probably heard about the Hossō Monk Takuitsu. … [Page 96] The dispute between Saichō and Takuitsu covered a wide range of problems, including the proper method of classifying the Buddha’s teachings, the evaluation of Tendai methods of exegesis of the Lotus Sūtra, and the criticism of various Tendai doctrines and meditations. Both men offered detailed and penetrating arguments in support of their positions. …

[Page 105-106] In its later stages, the debate focused on the exegesis of the Lotus Sūtra, the most authoritative scripture for the Tendai School.

Saichō often referred to his own school as the Tendai Hokkeshū, the Tendai School of Lotus Sūtra interpretation. It was not the only school which interpreted the Lotus Sūtra, since both the Hossō and Sanron schools had long traditions of exegesis of the Lotus Sūtra. Thus Saichō’s task was to show that the Tendai interpretation was the most authoritative one.

Tokuitsu followed the orthodox Hossō interpretation, as it was presented in Tz’u-en’s (632-682) commentary, the Fa hua hsüan tsan. According to Tz’u-en’s writings, the Buddha had a hidden purpose in preaching the Lotus Sūtra. He wanted to encourage people of undetermined nature to strive to become bodhisattvas, rather than being content with merely becoming or striving to become arhats or pratyekabuddhas. The One-vehicle doctrine was an expedient teaching (gonkyō) directed toward those of undetermined nature. The claims of the Lotus Sūtra that it was the ultimate teaching (jitsukyō) were an expedient designed to encourage this particular class of practitioner and were not to be considered as teachings which were universally valid. Predictions in sūtras that certain people would attain Buddhahood were said to refer to the individual’s possession of the gyōbusshō and to not have any general significance. Statements that all beings had the Buddha nature, such as that by the bodhisattva Jōbukyō (Never-disparaging), were said to refer only to the inactive ribusshō.

In contrast to the Hossō position presented above, Saichō believed that the Lotus Sūtra was the Buddha’s ultimate teaching, a direct revelation of the Buddha’s enlightenment, which was valid for all men and not just intended for one particular group. Saichō supported his arguments by referring to passages in the Lotus Sūtra that stated that the sūtra was indeed the Buddha’s ultimate teaching, by defending the Tendai classification of Buddhist doctrine, and by attacking the Hossō classification of Buddhist doctrine. The defense and exegesis of the The teachings of the One-vehicle, the universality of salvation, and the speedy realization of salvation were eventually accepted as standard Buddhist teachings throughout Japan. The new schools of the Kamakura reformation developed out of the Tendai School and adopted the positions that Saichō had defended, though not without changes. Even some Hossō monks such as Ryōhen (1194-1252) tried to reconcile the differences between Hossō and Tendai by devising positions which allowed for universal salvation and the quick attainment of salvation.