Tue Trung Thuong Si (Vietnamese: Tuệ Trung Thượng Sĩ, Hán Việt: 慧中上士) (1230–1291) is recognized as one of the most significant Buddhist masters of medieval Vietnam, a Thiền (Zen) teacher and a poet.
Tran Tung by his lay name (Vietnamese: Trần Tung / 陳嵩), master Tue Trung was the eldest son in a branch of the royal clan of Tran. He was the elder brother of the Queen of Vietnam, Nguyên Thánh Thiên Cảm (wife of King Tran Thanh Tong and mother of King Trần Nhân Tông), and of Tran Hung Dao who was to distinguish himself as the victorious commander of Vietnamese forces that successfully confronted the Sino-Mongolian invasion of Kublai Khan.
In these campaigns, in 1285 and 1288, Tran Tung was among the generals.[1]
After that, he retreated from worldly activities and became a Buddhist practitioner.
His teacher was a monk named Tieu Dao, a representative of the Wu Yantong lineage of Buddhism, named for its founder, a student of Baizhang Huaihai who had come to Vietnam. Tue Trung is considered Tieu Dao's best pupil.[2] He would not leave home for monastery, but his vast education and his ability to explain the Buddhist doctrine made him the most famous Buddhist teacher of his time.
In his turn, Tue Trung made his spiritual heir Trần Nhân Tông, the king who after abdication founded the first Vietnamese tradition of Buddhism, called the Trúc Lâm (Bamboo Grove) school.
Via Trần Nhân Tông, Tue Trung is part of the lineage of such modern Buddhist masters as Thích Nhất Hạnh.
Being essentially a Chan Buddhist tradition, the teaching of Tue Trung emphasized non-duality up to demonstrative negation of the value of formal meditation and rituals.
The main written heritage of Tue Trung, «Analects of Tue Trung Thuong Si» where Buddhist truths are taught in form of dialogue, survived to our days. Several of Tue Trung's poems are still cited.
Tue Trung became a legendary master often referred to in Buddhist lectures and literature. The most popular is the example of him stepping on horse's manure in silent reply to the question of the nature of Buddhism.[3] He is being actively referred to as a central Vietnamese Buddhist image to this day.[4]