肇論新疏 3.128

3.128

譬猶幽谷之響、明鏡之像，對之弗知其所以來、隨之罔識其所以往，恍焉而有、惚焉而亡，動而逾寂、隱而彌彰，出幽入冥，變化無常。

He is like an echo in a secluded valley, or an image in a clear mirror: facing it, one does not know where it comes from; following it, one cannot perceive where it goes. Suddenly it appears, and abruptly it vanishes; moving, it becomes ever more silent; hidden, it becomes all the more manifest; emerging from obscurity and entering into darkness, his transformations are without constancy.