The definition of the One Vehicle 一乗 is a key issue in the East Asian Buddhism. Many scholar-monks discussed the ten principles 十義 explained in a verse of the Mahāyānasaṃgraha 摂大乗論, the ten point explanation of for whom the Buddha taught and of the Buddhaʼs intentions in preaching the One Vehicle.
This paper examines how the interpretations of the ten principles have developed in the Sanron school 三論宗. Among the monks of this school, the ten principles were traditionally discussed according to the thesis of the Yisheng foxing jiujing lun 一乗仏性究竟論 written by Fabao 法宝 （fl. 7-8c）. The Ichijō Busshō enichi shō一乗仏性慧日抄 written by Enshū 円宗 （fl. 9c） has almost the same interpretation of the ten principles as Fabaoʼs theory. In the medieval period, Chinkai 珍海 （1091-1152） also took up the ten principles using the Yisheng foxing jiujing lun as a starting point for his discussion in the Sanron genshō mongiyō三論玄疏文義要. However, he set Jizangʼs 吉蔵 （549-623） interpretation of the One Vehicle as his theoretical pillar to elaborate his exegesis.
