Jianzhi Sengcan (鑑智僧璨; Wade-Giles: Seng-tsan) was the Third Patriarch of Chan, the disciple of Huike, and teacher of Daoxin. He is most famous for his poem, the Hsin Hsin Ming or Faith Mind Inscription, which is widely considered to be one of the most concise expressions of Chan in the canon.
Countless records, legends and stories have been told about Sengcan through the ages. However, Sengcan is one of those figures about whom much has been told but very little is known for certain. Among the first six patriarchs of Chan Buddhism, Sengcan is the only one without a biography in any of the three major monastic biographical anthologies in medieval China. Throughout Xu gaoseng zhuan 續高僧傳 (Further Biographies of Eminent Monks), the monastic biographical collection that covers Sengcan’s time and in which one might expect a biography for him, only twice is anything relevant to Sengcan mentioned. One occurs when a certain Meditation Master Can 粲禪師 is introduced as a successor to Huike, while the other consists in a brief reference to a monk called Sengcan, who was known to have performed a miracle at a place close to the mountain at which Daoxin, the future fourth Chan patriarch, studied under two unspecified monks, one of whom later Chan histories identified as Sengcan. (1)
While very little is known about the historical Sengcan (who is likely a composite of several figures), tradition holds that he approached Huike at a time when the Second Patriarch was master of a large congregation. Sengcan was suffering from a skin disease, and after a brief dialogue with Huike, he had a great realization and subsequently recovered from his illness. After Huike gave the transmission of the teaching to Sengcan, he advised him to go into hiding for the time being. Historically, the time when Sengcan is supposed to have lived saw an anti-Buddhist persecution that lasted for several years. The persecution eventually subsided, and is often held up as the reason for the sparse details surrounding Sengcan's life and his relative seclusion when comapred to Huike and Daoxin, his immediate predecessor and successor, respectively - both of whom seem to have taught many disciples.
Sengcan's period of hermitage lasted from 9-12 years (depending on which source is used), where he dwelt on Mt. Wangong with another meditation master named Ding. It was during this time that Daoxin encountered Sengcan while searching for a teacher, and studied with him for the bulk of this time. Afterwards, Sengcan left for Luofo and instructed Daoxin to carry on his teaching. Then, depending on which source is used, Sengcan either died at Luofo, or else returned to Mt. Wangong and died there three years later.
The most likely scenario, according to Chen, is that Sengcan was composited from at least three figures in order to satisfy three different criteria. When the East Mountain School (The Northern School) was seeking to legitimize their teaching as descended from Bodhidharma, a link was required between Daoxin and Huike. Therefore, a candidate for Third Patriarch of Chan would have to have both learned from Huike and taught Daoxin. The earliest sources on Daoxin do not name his teacher, and simply state that he met two unnamed monks living on Wangong and learned from them for a period of ten years. When it comes to Huike's disciples, a figure named 'Meditation Master Can' is named as his first disciple, which Chan scholars may have taken to means that he was the foremost disciple. Finally, there were at least two prominent figures named Sengcan that lived and taught between the time when Huike and Daoxin would have been teaching, one of which was recorded nearby Mt. Wangong around the time when Daoxin would have been there. As such, a speculative conclusion would be that: one of the two unnamed monks had to be connected with a student of Huike; there was a student of Huike with the name 'Can'; and finally that there was a figure named Sengcan in the right place at the right time, and as such Meditation Master Can's identity was correlated with Sengcan.
One day on the mountain Master Huike met a lay practitioner who had a skin disease. The layman asked the master, “This disciple's body is is bound up in illness. Master, please help me repent for my sins.”
The master said, “Bring me your sins and I will absolve them for you.”
After a pause the layman said, “Looking for my sins, I can't find them anywhere.”
The ancestor said, “There, I have absolved your sins. From now on live in reliance on your true nature, on practice, and on spiritual community.”
Master Huike ordained the layman and gave him the name Sengcan. His illness subsided, and he later became the master's most famous disciple.
(1) Jinhua Chen; FACT AND FICTION: THE CREATION OF THE “THIRD CHAN PATRIARCH” AND HIS LEGENDS