成唯識論了義燈 2.29

2.29

重性通常無常，若爾，如何唯現量耶？唯父母微是常非現故，答：論無文解，義准云通現，比無妨。又香唯無常，如何通非現？答：香雖無常不廢但在子上，故通非、現。

Heaviness (gurutva) is common to the permanent and the impermanent. If so, how can it be only direct perception (pratyakṣa)? Because only the parent atoms are permanent and non-perceptual. Answer: The treatise has no textual explanation; inferred by principle, it is said that it is common to direct perception and inference without impediment. Furthermore, odor is solely impermanent; how can it be common to non-perceptual? Answer: Although odor is impermanent, it is not precluded from residing solely on the child [atom], and therefore it is common to non-perceptual and direct perception.