法華玄論 5.27

5.27

Answer: Just as provisional wisdom can lead into real wisdom, real wisdom is that which is penetrated into. Named from that which is penetrated, it is said that "the gate of their wisdom": wisdom is real wisdom, and gate is provisional wisdom; this provisional wisdom is termed the gate to the household of real wisdom. For example, the three gates of liberation are named from that which is penetrated: liberation is the fruit of nirvāṇa that is penetrated; the three emptinesses can lead practitioners through to attaining nirvāṇa, hence they are called gates of liberation. Furthermore, when worldly people say "gate of the Buddha", "gate of humans", and so forth, these are all gates [named] from that which is penetrated. As for deriving the name based on intrinsic essence: skillful means in its intrinsic essence is open and penetrating; hence it is called a gate. The true mark is also like this. It is like saying "bamboo gate" or "plank gate": the very substance of the gate is bamboo or planks, so it derives its name based on its intrinsic essence.