肇論新疏 2.198

2.198

The great expedient means benefits beings only when there is no stimulus; when stimulated, it unfailingly responds, as trustworthy as the four seasons. "Directly" means uprightly. "Vacuous non-being" borrows words from Laozi: prajñā's substance is wonderfully serene and transcends marks, which is called "vacuous"; it eternally exhausts delusion and grasping, which is called "non-being." From "This can neither" onward, he concludes. Great Master Xianshou says: "Neither arising nor ceasing, it is not altered by the four characteristics." This means that since it takes utmost vacuity as its nature, its coming upon stimulus is not arising, and its fading upon stimulus is not ceasing; hence he says, "can neither be made," and so forth.