肇論新疏 2.159

2.159

若無知故不取，聖人則冥若夜遊，不辨緇素之異；若知然後不取，知則異於不取矣。

If it does not grasp because of non-knowing, the sage would be dark as if walking by night, not distinguishing the difference between black and white. If it knows and only thereafter does not grasp, then knowing is different from not grasping.