Saichô 最澄, one of the buddhist founders in the Heian 平安 era, had been fiercely discussing for five years with Tokuichi 徳一, the learned priest of the Hossô 法相 sect who lived then in Aizu 会津 and was an earnest successor to the theory of the logical Yukayuishiki 瑜伽唯識 which was for the first time introduced into the eastern Asia by Hsüan-tsang 玄弉 of T'ang 唐. Saichô, confronted with this new theory, in turn claimed preceding theories of various sects to strengthen his own stand-point. Buddhist dogma in the Nara 奈良 era accepted miscellaneously various theories used by him. These discussions, we may say, enable us somewhat to revive the dogma in the Nara era.