大般涅槃經義記 7.61

7.61

上來別解，下總釋之。言「以性故，生住異壞皆是常」者，隨事分齊，各自守性恒有為常。「念念滅故不說常」者，於法分齊，運運遷滅故是無常。理實念念亦生、住、異，據終說滅，「是大涅槃能斷滅故名無常」者治滅無常。

The above was the specific explanation; below is the general interpretation. The statement, "Because of nature, arising, abiding, alteration, and destruction are all permanent," means that according to phenomenal demarcation, each maintaining its nature as constantly existent is permanent. "Because of ceasing thought-moment by thought-moment, they are not spoken of as permanent" means that from the standpoint of dharma demarcation, they shift and cease from moment to moment; hence they are impermanent. In truth and actuality, in each thought-moment there is also arising, abiding, and alteration, but it speaks of cessation based on the culmination. "Because this Great Nirvāṇa can sever and extinguish them, it is called impermanent" refers to the impermanence of remedial cessation.