The essence of the philosophy of Master Wonhyo (元曉, 617‑86) centrally focused on interaction between the secular world and the spiritual world. His notion of spirituality places emphasis on deeper interaction and conventional communication between those two. Master Wonhyo’s philosophy remains within the context of Mahayana Buddhism, featuring certain commonalities with the Vimalakirti Sutra. We know that Wonhyo wrote the Yumagyeong Jongyo (Thematic Essentials of the Vimalakirti Sutra) in one volume, and the Yumagyeong Yakchan (Brief Commentary on the Vimalakirti Sutra) in seven volumes, although these books were lost. His understanding was based on Bodhisattva practice as well as the spirit of Layman Vimalakirti (Yuma in Korean). The trend of modern research is to only focus on Master Wonhyo, and place less emphasis on his alter-ego Layman Soseong’s position and activities. That is to say, researchers overlook his role as a layman who lived with the common people for a long time and influenced them in many ways. His conception of spirituality was not to escape from worldly affairs and the secular world, but rather he sought profound engagement with society and holy nirvana within this world. Moreover, his religious practice didn’t intend to escape from this sin-tainted world, but rather one’s freedom to experience the Jeongto (淨土, Pure Land) within this world. His communication with common people was not only his determination but also his real understanding that the Jeongto and the notion of Nirvana are deeply entrenched within this Sabasegye (娑婆世界, sahā, samsara, the secular world of suffering). Wonhyo knew that renouncing the world (becoming a monk) meant leaving home and all worldly affairs behind; however, he was worried that such a self-centered practice would injure Mahayana Buddhism’s superior objective of salvation for all. This philosophy of non-dualism is a core idea of his spiritual quest.