瑜伽論記 4.385

4.385

最極通達者，是青瘀等觀等者，此說白骨觀是不淨觀中最極通達義，是青瘀等。後勝次第未後逾越貪等觀義，第二番云：初、不淨觀觀察內身；後、不淨觀通達法性。此依所緣境界事理淺深緣起差別顯二不淨觀，根本觀中不淨境及性二類別故，是故前言斷滅對治。

Regarding 'utmost penetration is the contemplation of livid discoloration, etc.': this explains that the contemplation of white bones is the meaning of 'utmost penetration' among the contemplations of impurity; it is the contemplation of livid discoloration and so forth. In the subsequent superior sequence, it is the meaning of the contemplation that subsequently transcends greed, etc. The second set states: The first contemplation of impurity observes the internal body; the latter contemplation of impurity penetrates the nature of phenomena (dharmatā). This demonstrates the two contemplations of impurity in terms of the differences in the causal conditioning of the depth and shallowness of phenomena and principle in their objective spheres, because within the root contemplation, the impure object and the nature are of two different kinds; therefore it was earlier called the 'severing and eliminating counteractive measure'.