成唯識論述記 2.776

2.776

述曰：生等假法，如龜毛等，體是無法，非因緣故。種子望法即是因緣，故體實有。問：生等既如無，應非行蘊攝。答：依法施設故，故是行蘊收。然法非果，生非是因，即於法上假施設故，亦有唯於現行等法，或種上立，故例不同。種子非現行，因、果差別故。

The Commentary states: Nominal dharmas such as origination are like the hair of a tortoise: their substance is a nonexistent dharma, because they are not cause-and-condition. Seeds with respect to dharmas are precisely cause-and-condition; therefore, their substance is substantially existent. Question: Since origination and the like are like nonexistence, they should not be subsumed under the saṃskāra-skandha. Answer: Because they are designated depending on dharmas, they are included in the saṃskāra-skandha. However, dharmas are not effects, and origination is not a cause; they are merely nominally designated upon dharmas. There are also those established solely upon active phenomena and the like, or established upon seeds; hence the cases are not analogous. Seeds are not active phenomena, because there is a difference between cause and effect.