瑜伽論記 4.301

4.301

違順二相不相應故者，緣違境心低，緣順境心昂。今無二相，名不低昂。又壞世諦違俗境，名低；執心存立順真境名昂，無相行離二，名不低昂。此不壞世諦即不思惟一切相，不厭不壞等，名不低；此於無相界正思惟故，不順堅執，名不昂。

Regarding "because of non-association with the two signs of adversity and favor": when focusing on an adverse object, the mind is low; when focusing on a favorable object, the mind is exalted. Now, because both signs are absent, it is named "neither low nor exalted." Furthermore, ruining conventional truth and conflicting with worldly objects is called "low"; an adhering mind establishing and favoring real objects is called "exalted." The signless practice is separated from both, and hence is called "neither low nor exalted." Here, not ruining conventional truth is not conceptualizing all signs, not reviling or destroying them, etc., which is called "not low"; correctly contemplating the signless realm and not complying with rigid grasping is called "not exalted."