Very little can be stated with certainty about Sosan’s personal life, and this very absence of detail has become part of his spiritual image. The sources that speak of him are late and often hagiographical, so even basic facts such as his dates, birthplace, and family background remain unclear. His lay name, social status, and occupation before ordination are not reliably recorded, and his early life is essentially veiled in silence. Tradition simply remembers him as the Third Patriarch of Chan, placed between Huike and Daoxin in the lineage, rather than as a figure with a well-documented worldly biography.

The stories that do exist focus less on external biography and more on spiritual turning points. A widely repeated account describes him as suffering from a serious illness—often portrayed as a disfiguring skin disease—and approaching Huike in search of liberation from his suffering. This encounter is framed not as a medical cure but as a profound shift in understanding, in which the insubstantial nature of “sin” or karmic burden is revealed. From that point, he is said to have become a close disciple of Huike, eventually receiving the robe, bowl, and Dharma seal that symbolize transmission in the Chan tradition.

Later narratives also portray Sosan as a figure of seclusion and quiet endurance. During periods of Buddhist persecution, he is said to have withdrawn into the mountains, living in obscurity and teaching only a small circle of students. This image of a teacher hidden in remote places, avoiding public prominence, reinforces the sense that his life was shaped more by inner practice than by institutional status. His most renowned disciple is Daoxin, remembered as the Fourth Patriarch, who is likewise said to have met him in the mountains and studied with him for years.

Sosan’s legacy is thus carried less by concrete biographical data and more by texts and stories that crystallize a certain spirit of early Chan. He is traditionally associated with the *Xinxin Ming* (“Faith in Mind”), a work that later generations have regarded as a classic expression of non-duality and trust in the fundamental nature of mind, even though modern scholars question whether he actually authored it. The historical reliability of many details—his illness, his wanderings, the exact dates of his life and death—remains doubtful, yet these narratives convey how the tradition chose to remember him. What emerges is the figure of a largely anonymous monk whose obscurity itself becomes a teaching: a life in which the outer record is thin, but the inner transmission is held to be complete.