成唯識論述記 1.612

1.612

述曰：此中量云：或應本極微有麁量德合；與麁果色處無別故；如麁色果。以量既等，即一處住體相涉入，名處無別。文無別因，意說相入。相入即是量等子微之義。子微今以量無別為因，顯父母亦得；父母以處無別為因，顯子微亦得。互影顯也。

The Commentary states: The syllogism here is: Or the original atom should combine with the quality of coarse magnitude; because there is no difference in its location from that of the coarse material effect; just like the coarse material effect. Since their size is equal, residing in one location, their substances interpenetrate, which is called 'no difference in location.' Although the text mentions no other reason, its intended meaning is interpenetration. Interpenetration precisely means that the child-atom is equal in size [to the parent]. Using 'no difference in size' as the reason for the child-atom here demonstrates that the parent [atoms] also entail it; using 'no difference in location' as the reason for the parent [atoms] demonstrates that the child-atom also entails it. They mutually illuminate each other.