十不二門指要鈔 2.54

2.54

Second, from "Dharma-nature..." down, clarifying the function of defilement and purity: since the substance is completely turned, the function is also symmetrically overturned. Since Dharma-nature acts as ignorance, it gives rise entirely to the function of ignorance; since the function is bound by attachment, it is called defilement. If ignorance acts as Dharma-nature, it gives rise entirely to the function of Dharma-nature; since the function is unhindered, it is called purity.