Kuiji and Wŏnch’ŭk's understanding of the Tathāgatagarbha

In this paper, I investigated how Kuiji(窺基) and Wŏnch’ŭk(圓測) understood Tathāgatagarbha using the concept of twofold Buddha-nature(二佛性), which combines 理性 and 行性 as a pair for interpretation. Firstly, I pointed out the commonalities and differences between Kuiji and Wŏnch’ŭk's perspectives. Both agree on the existence of 理性 and 行性, but they differ in their explanations of 行性. Kuiji describes it as 種姓(gotra) or 種子(bīja), while Wŏnch’ŭk describes it as six pāramitā. Additionally, I argued that the theory of twofold Buddha-nature originated in China rather than in India, complementing existing studies. This conclusion is based on the absence of the twofold Buddha-nature concept in texts like the 『大乘莊嚴經論』 and 『攝大乘論釋』, which mention Tathāgatagarbha, and the understanding of Indian Vijñānavādin, who perceived Tathāgatagarbha solely as Tathatā. I pointed out the distinctive feature of Kuiji and Wŏnch’ŭk's interpretation of the Tathāgatagarbha, compared to Indian Vijñānavādin, which attribute a conditional aspect to Tathāgatagarbha through the concept of 行性.