瑜伽論記 8.143

8.143

此五行中，初變異行，即前所明八種因緣十五種十六種等變異是。第二滅壞行，即前所明比度有剎那生滅等是也，故言已辨二行，今第三云何復由別離行故觀無常性。

Among these five aspects, the first is the aspect of alteration, which is precisely the alterations of the eight kinds of causes and conditions, the fifteen kinds, the sixteen kinds, and so forth explained earlier. The second is the aspect of destruction, which is precisely what was explained earlier concerning the inferential deduction of moment-by-moment arising and ceasing. Therefore it says "two aspects have already been explained; now third, how does one further contemplate impermanence through the aspect of separation?"