成唯識論述記 8.648

8.648

述曰：雖實亦由諸法現行生死相續，而種子相續一切時有，非如現行多間斷故，頌中偏說種子，云由業習氣等。

The Commentary states: Although it is true that the continuation of samsāra is also due to the active manifestations of all phenomena, yet the continuation of seeds exists at all times, unlike active manifestations which have many interruptions; therefore the verse specifically mentions seeds, saying "due to the latencies of karma," and so forth.