Within the traditional Zen lineage, Sosan (Sengcan, Sōsan) is honored as the Third Patriarch of Chinese Zen, standing between Huike as Second Patriarch and Daoxin as Fourth. His role is to receive the Dharma transmission from Huike and then pass it on to Daoxin, thereby sustaining the continuity of the “mind-to-mind transmission” that traces back to Bodhidharma. In this way, he functions as a vital link in the early patriarchal chain, ensuring that the emerging Chan tradition maintains a sense of unbroken spiritual inheritance. The lineage presents him as bridging the more legendary beginnings of Zen with the increasingly documented and institutional forms that follow.

Sosan’s place in the tradition is often described as that of a stabilizing and transitional figure. He stands at the threshold where Zen begins to take clearer shape as a distinct school within Chinese Buddhism, moving from a primarily Indian-influenced, semi-legendary phase toward a more settled Chinese context. Through this position, he helps to ground the early, somewhat elusive teachings in a form that can be carried forward by later masters. His role is thus less about dramatic innovation and more about faithfully receiving, embodying, and transmitting the core insight so that it can flourish in subsequent generations.

Traditionally, Sosan is associated with the text known as the “Xinxin Ming” or “Faith in Mind,” a work regarded as one of the earliest and most influential Zen writings. This poem gives voice to central Chan themes such as non-duality, the unity of apparent opposites, and the importance of moving beyond conceptual thinking. It expresses a trust in mind itself as the locus of awakening, and articulates a perspective that later Zen schools would repeatedly draw upon. Through this association, Sosan is seen not only as a guardian of the lineage, but also as a figure whose teaching helped shape the philosophical and contemplative atmosphere in which Chinese Zen would mature.