十不二門指要鈔 2.53

2.53

初、明染淨體者，三千寂體即寂而照，既無能照亦無所照，名為法性，以本愚故妄謂自他，三千靜明全體暗動，即翻作無明，本來不覺，故名無始。若識此者，即照無明體本明靜，即翻為法性。

First, clarifying the substance of defilement and purity: the quiescent substance of the three thousand [realms] is immediately quiescent and yet illuminating. Since there is neither an active illuminator nor an object illuminated, it is named Dharma-nature. Because of fundamental foolishness, one falsely posits self and other; the quiescent clarity of the three thousand realms in its entire substance becomes dark and agitated, which then turns into ignorance. Being fundamentally unawakened, it is called beginningless. If one realizes this, then one illuminates that the substance of ignorance is fundamentally clear and quiescent, which then turns back into Dharma-nature.