Wonhyo (617–686 CE) was one of the leading thinkers, writers and commentators of the Korean Buddhist tradition. Essence-Function , a key concept in East Asian Buddhism and particularly Korean Buddhism, was refined in the syncretic philosophy and world view of Wonhyo.
As one of the most eminent scholar-monks in Korean history, he was an influential figure in the development of the East Asian Buddhist intellectual and commentarial tradition. His extensive literary output runs to over 80 works in 240 fascicles, and some of his commentaries, such as those on the Mahāyāna Mahāparinirvāṇa Sūtra and the Awakening of Faith in the Mahayana, became classics revered throughout China and Japan as well as Korea. In fact, his commentary on the Awakening of Faith helped to make it one of the most influential and intensively studied texts in the East Asian Mahāyāna tradition. Chinese masters who were heavily influenced by Wonhyo include Fazang, Li Tongxuan, and Chengguan. The Japanese monks Gyonen, Zenshu and Joto of the Kegon school were also influenced by him.
With his life spanning the end of the Three Kingdoms of Korea and the beginning of Unified Silla, Wonhyo played a vital role in the reception and assimilation of the broad range of doctrinal Buddhist streams that flowed into the Korean peninsula at the time. Wonhyo was most interested in and affected by Buddha-nature, East Asian Yogācāra and Hwaeom thought. However, in his extensive scholarly works, composed as commentaries and essays, he embraced the whole spectrum of the Buddhist teachings which were received in Korea, including such schools as Pure Land Buddhism, East Asian Mādhyamaka and the Tiantai.