大乘義章 2.7

2.7

Next, speaking of the three gates in reference to nirvāṇa. Within nirvāṇa there are essence, characteristics, and function: naturally pure nirvāṇa serves as its essence; expedient nirvāṇa serves as its characteristics; and responsive nirvāṇa serves as its function. The quiescence of that essence is called the gate of emptiness; the meaning of the quiescence of characteristics is called signlessness; the quiescence of function is called actionlessness.