Jinul (知訥, प्रज्ञापाल - Prajñāpāla; ཅི་ནུལ། ci nul Chinul, universally revered across Korea, China, and East Asia as Bojo Guksa - 普照國師, National Preceptor Universal Illumination, and fondly known by his self-chosen pen name Moguja - 牧牛子, Oxherder), acclaimed throughout Korean Buddhist history as the greatest reformer and doctrinal architect of the Jogye Order of Korean Seon (Chan / Zen) Buddhism, stands as a towering 12th century and 13th century contemplative master and synthesizer. With his year of birth in 1158 and his year of death in 1210, Jinul was born into the aristocratic Jeong clan in Dongju (modern Seoheung) in Hwanghae province on the Korean Peninsula to his father, Jeong Gwang-u, a scholar at the Goryeo National Academy. Suffering from severe, chronic physical frailty from early childhood that defied all medical remedies, Jinul was saved when his father prayed fervently to Shakyamuni Buddha and vowed to dedicate the boy to the monastic life, whereupon the child recovered completely; fulfilling this sacred vow at age seven, Jinul practiced fearless renunciation, took formal refuge in the Buddha, the Dharma, and the Sangha, entered the monastic order under Seon master Jonghwi of the Sagulsan mountain school, and received full monastic ordination in the Vinaya Pitaka lineage while upholding impeccable precepts and ethical conduct.
Distressed by the deep corruption, aristocratic factionalism, and bitter rivalry dividing the Seon (meditation) schools and the Gyo (doctrinal) schools of Goryeo dynasty Korea, Jinul passed the royal monastic examination in 1182 at Bojesa Temple in Gaegyeong (modern Kaesong), only to immediately renounce all official rank and prestige to form a secret pact with fellow reform-minded monks to establish a pure retreat community dedicated solely to meditation, mindfulness, and wisdom. Retreating southward to Cheongwonsa Temple in Changpyeong and later to Bomunsa Temple on Mount Hagasan, Jinul experienced three transformative, progressive breakthroughs of awakening triggered by reading pivotal Mahayana texts rather than relying on a single living teacher: first, realizing that the luminous mind itself is the Buddha while reading Huineng's Platform Sutra of the Sixth Patriarch (Taisho Number 2008 in the Chinese Tripitaka); second, realizing that the mind-ground of Seon and the cosmic interpenetration of the Avatamsaka Sutra (Taisho Number 279 and Toh Number 44 in the Tibetan Tripitaka) are completely identical while reading Li Tongxuan's Xin Huayan Jing Lun; and third, shattering all remaining conceptual clinging while reading the letters of the Song dynasty Chan master Dahui Zonggao (1089–1163).
In 1190, Jinul moved to Geojosa Temple on Mount Gongsan and formally inaugurated the historic Jeonghye Gyeolsa (定慧結社, Samadhi and Prajna Community), publishing his famous manifesto Gwon-su Jeonghye Gyeolsamun ( The Compact of the Samadhi and Prajna Community) to summon monastics and laypeople alike back to authentic ethical conduct, single-pointed concentration, and piercing insight. Ten years later, in 1200, as hundreds of disciples flocked to join his community, Jinul relocated his monastery to Gilsangsa Temple on Mount Jogye (later renamed Songgwangsa Temple by royal decree of King Huijong of Goryeo), establishing the institutional and spiritual heartland of the Korean Jogye Order.
Literarily, Jinul composed a lucid, extraordinarily influential corpus of treatises preserved in the Korean Buddhist canon and the Chinese Tripitaka that permanently shaped East Asian Seon thought. Among his supreme masterpieces are the Susim Gyeol (修心訣, Secrets on Cultivating the Mind), the Jinsim Jikseol (真心直說, Straight Talk on the True Mind), the Gyeolsim Hwasimnon (Resolving Doubts About Observing the Hwadu), and his monumental doctrinal summa, the Beopjip Byeolhaengnok Jeoryo Byeongip Sagi (法集別行錄節要並入私記, Excerpts from the Dharma Collection and Special Practice Record with Personal Notes), which systematically integrated the teachings of Guifeng Zongmi (780–841) into Korean Seon practice.
Philosophically and contemplatively, Jinul bridged the fierce divide between Seon and Gyo by adapting Guifeng Zongmi's celebrated formula of Sudden Awakening Followed by Gradual Cultivation (Dono Jeomsu, 頓悟漸修). Demonstrating that a practitioner first experiences sudden awakening (dono) upon recognizing that their own primordially pure, luminous Buddha-nature (tathagatagarbha) is already identical to the Buddha, Jinul explained that because deeply entrenched habitual tendencies from beginningless rebirth still linger like residual fragrance in an empty vessel, the practitioner must continue with patient, gradual cultivation (jeomsu) through balanced samadhi (concentration) and prajna (wisdom) until non-dual realization becomes completely effortless.
Harmonizing Nagarjuna's Madhyamaka dialectics regarding emptiness (शून्यता - śūnyatā; སྟོང་པ་ཉིད། stong pa nyid Tongpanyid) and dependent origination with Asanga's Yogacara phenomenology, Chengguan and Fazang's Huayan metaphysics of dependent co-arising, and the Mahaparinirvana Sutra (Taisho Number 374 and Toh Number 119), Jinul also pioneered the integration of Dahui Zonggao's Ganhwa Seon (看話禪, critical-phrase or hwadu contemplation) into Korean monasticism—guiding disciples to investigate existential doubts such as Zhaozhou's Mu (No) until attachment to the five aggregates, anatta, emptiness of self, and karma collapses into direct, non-conceptual right view and non-attachment.
Throughout his decade as abbot of Songgwangsa Temple on Mount Jogye—where he trained hundreds of ordained monastics and lay practitioners, including his foremost successor Jin-gak Hyesim (1178–1234)—Jinul emphasized that lofty Seon realization must always express itself through uprooting the three poisons of greed, hatred, and delusion and embodying Shakyamuni Buddha's foundational teachings on the Four Noble Truths, the Noble Eightfold Path, anicca, and dukkha across the six realms, cultivating generosity, merit, loving-kindness, compassion, equanimity, skillful means, and universal bodhicitta.
Passing into final parinirvana at Songgwangsa Temple on Mount Jogye in 1210 at the age of fifty-two seated upright in the lotus posture holding his monastic staff after delivering a final spontaneous Dharma discourse to his assembled disciples, Jinul was posthumously honored by King Huijong of Goryeo with the title Bojo Guksa (National Preceptor Universal Illumination) and enshrined in the Gamno Tap stupa. Revered as the true spiritual founder of modern Korean Jogye Buddhism and inspiring generations of masters from Jin-gak Hyesim and Taego Bou to Seongcheol, Jinul stands forever alongside Wonhyo, Uisang, Guifeng Zongmi, Nagarjuna, and Longchenpa as a supreme guardian of the Middle Way.