Wonhyo (617-686) is a great Buddhist priest during the Unified Silla Kingdom. His family name is Seol. He was born in Apryang-gun, Gyeongsan. At the age of 15, he entered a Buddhist monastery. An episode tells of how he attained enlightenment. On his way for study to Tang China with the priest Uisang, he happened to stay one night over in a cave. In the middle of night, Wonyo was awakened by severe thirst and drank water which turned out to be stagnant water in a human skull. Then immediately, he obtained enlightenment, declaring that "the ultimate truth lies not outside oneself but within oneself." Then he turned his back to Silla.
Wonhyo is not only a luminous Buddhist scholar but thinker. He also contributed greatly to turning aristocratic Buddhism to the people's religion. His thought is known to have been not biased to one sect but harmonized with one truth in Buddhism. He fathered Seol Chong from marriage to Princess Yoseok.