瑜伽論記 18.378

18.378

除去修者，由觀身不淨，不淨影像現前除遣淨相等。言如楔出楔，方便者，謂修定作意有多品類故，所緣相亦有麁細，以後作意捨前麁漸漸除棄故也。言以輕安身，除麁重身者，色界輕安而在身故，令行者身輕安除去欲界種子，種子麁重麁重令身麁重故須除也。

Regarding cultivation of removal: through contemplating the impurity of the body, the image of impurity becomes manifest, removing pure marks and the like. Where it says 'like a peg knocking out a peg, an expedient means': this means that because there are many grades of mental application in cultivating concentration, the marks of their objects also have coarse and subtle levels; using a later mental application to abandon an earlier coarse one gradually removes and discards them. Where it says 'using a pliant body to remove a coarse body': because pliancy of the form realm resides in the body, it causes the practitioner's body to become pliant, removing seeds of the desire realm; the seeds are coarse and heavy, and their coarseness makes the body coarse and heavy, so they must be removed.