大般涅槃經義記 8.129

8.129

The nature being named ultimate emptiness is the first gate. The gate of buddha-nature vastly encompasses all kinds of meanings of the dharmadhātu; now this is spoken of provisionally in terms of the single gate of emptiness. Speaking of the nature with reference to defilement easily accords with emotional grasping; therefore it is spoken of as empty. How is the nature empty? Roughly speaking, there are two meanings: first, being free from marks is called empty; although its essence is truly existent, it is without any single mark, just as pure sarpirmaṇḍa is without marks of blue, yellow, red, white, and so forth; it is also like the mental consciousness of all sentient beings, which, although its essence is existent, is without marks of large, small, long, short, and so forth. Furthermore, it is like the buddha-body: its essence is truly marvelous existence, yet it is without any single mark. What kinds of marks is it without? As Aśvaghoṣa says, it means it is not the mark of existence, nor is it the mark of non-existence; it is not the mark of neither existence nor non-existence, nor is it the mark of both existence and non-existence; it is not the mark of oneness, nor is it the mark of difference; it is not the mark of neither oneness nor difference, nor is it the mark of both oneness and difference; it is not the mark of self, nor is it the mark of other; it is not the mark of neither self nor other, nor is it the mark of both self and other. In this way, all discriminations of the deluded mind are entirely incongruent with it; it is exclusively the realm of realization.