金光明經玄義 1.18

1.18

What are the three kinds of buddha-nature? "Buddha" means awakened; "nature" means unchangeable. Unchangeable means neither permanent nor impermanent; like a store of gold within the earth, which celestial demons and outsiders cannot destroy, it is called the direct cause buddha-nature. As for the revealing cause buddha-nature: awakened wisdom is neither permanent nor impermanent; wisdom corresponds with the principle, like a person who well knows the gold store; this wisdom cannot be destroyed, and is called the revealing cause buddha-nature. As for the conditional cause buddha-nature: all are neither permanent nor impermanent; merits and wholesome roots assist the awakened wisdom to reveal the direct nature, just like weeding away refuse and digging out the gold store; it is called the conditional cause buddha-nature. One should know that each and every one of the three kinds of buddha-nature is permanence, bliss, self, and purity, neither dual nor distinct from the three virtues. Since the Suvarṇaprabhāsa serves as a metaphor for the three virtues, the three characters of Suvarṇaprabhāsa also serve as a metaphor for the three kinds of buddha-nature.