大般涅槃經集解 21.49

21.49

案僧宗曰：第三就相待明六行也。以生死為下、佛果為上，以上知下，所以而常；下不知上，故無常也。寄譬明如來住智慧之上，見五道生死也。借譬以明見，而物情於譬生滯，故迦葉仰諮，以拂斯迹也。

Sengzong comments: The third clarifies the six practices in terms of mutual relativity. Taking saṃsāra as lower and the fruit of buddhahood as higher: because the higher knows the lower, it is therefore permanent; the lower does not know the higher, therefore it is impermanent. Relying on an analogy, it clarifies that the Tathāgata abides above wisdom and sees saṃsāra in the five destinies. Drawing on an analogy to clarify perception, yet worldly sentiments become attached to the analogy, so Kāśyapa inquires upward to sweep away these traces.