成唯識論述記 3.85

3.85

述曰：即前六義，簡無為因。以有作用，故方能熏，猶如種子有生滅用，故能生果。

The Commentary states: This corresponds to the six meanings [of a seed] mentioned earlier, excluding unconditioned dharmas as causes. Only because it has function can it perfume, just as seeds have the function of arising and ceasing and therefore can produce fruitions.