This is a translation of the book that records Seongcheol’s 性徹 (1912–1993) sermons to audience with his explanations. Seongcheol was one of the most renowned Seon monks in modern Korea, who also served as the supreme patriarch of the Jogye Order of Korean Buddhism. He tried to recover the tradition of Korean Seon practice by organizing a Buddhist society at Bongamsa in 1947. He became the first head-monk (bangjang) of Haeinsa Monastery in 1967 and preached the dharma sermon for a hundred days (baegil beommun). He left many works, including the Han’guk Bulgyo ui beommaek (Dharma Lineages of Korean Buddhism, 1976) and the Bonji punggwang (Scenery of the Original Ground, 1982). This translation used the Seongcheol Seunim pyeongseok Seonmun jeongno (Seonmun jeongno with Seongcheol’s Annotation, 2015), consulting with the Jeongdok Seonmun jeongno (Perusal of Seonmun jeongno, 2022). The Seonmun jeongno 禪門正路 is a record of sermons that discuss the sudden awakening and hwadu investigation in Seon. It consists of nineteen chapters: (1) “To See Your Own Nature Is to Become a Buddha”; (2) “Sentient Beings Have Buddha Nature”; (3) “Two Types of Afflictions and False Thoughts”; (4) “Unsurpassed Perfect Enlightenment”; (5) “Realizing the Truth that All Dharmas Are Unborn”; (6) “No Thought Is the True Tenet”; (7) “Protecting No Mind”; (8) “Awake or Asleep, Being Consistent”; (9) “Gaining Life in Death”; (10) “Great Perfect Mirror-Like Wisdom”; (11) “Inside and Outside Are Brilliantly Clear”; (12) “Constantly Serene and Constantly Illuminating”; (13) “Discursive Awakening Followed by Gradual Cultivation”; (14) “Partial Penetration and Partial Attainment”; (15) “With Erudition There Is Only Discursive Knowledge”; (16) “Abrupt Exhaustion of All Contaminants”; (17) “A Clear-Eyed Patriarchal Master”; (18) “Mysteries and Essentials, Real and Provisional”; (19) “Eliminating the Seed of Buddhahood.” In this book, Seongcheol criticizes Bojo Jinul’s sudden awakening-gradual cultivation and insists the sudden awakening–sudden cultivation, which later triggered the intense debate of sudden and gradual in Korea.