The philosophical thought of knowing only the Fa Sect also contains profound Buddhist thought. In the Southern and Northern Dynasties, Xuanzang's translation of "Taking Mahayana" for studying and carrying forward the true meaning was puzzled by the theory of Buddha's nature, hoping to explore the canon directly and enlighten the confusion. He brought back the original books and thinking methods of the Yoga School, especially the Legalism School. In the early years of the Tang Dynasty, Xuanzang founded the yoga master's theory of land, legalism, epistemology and Dafayuan-Yilinzhang, which are the basic classics of the Sect. As its basic canon, the theory of yoga master's land is also called yoga school in the history of Buddhism. There are several doctrines of the only-knowing Sect, namely, only knowing twenty, becoming only knowing, being endless, breaking the color heart, only knowing unbounded, compiling, three-self, brief introduction of set theory, omniscient theory, praising the eight-knowledge track, following the right theory, highlighting the holy religion theory, anti-law theory and set theory.