大乘百法明門論開宗義決 1.81

1.81

謂前七識皆是種生等者。七識是果。種子是因。然因與果皆名體相。體即是相無差別也。凡因與果雖非定一不可定異。無別性故　即攬此種為第八識者。如唯識論第二卷云。阿賴耶識有其三相。一者因相。謂所持種能生染淨法故。二者果相。即現識體是善惡業異熟果故。三者自相。即此種現攝持因果為自相故。言自相者即自體義。既攝因果以為自體。故用種子為第八識。

Regarding "meaning that the former seven consciousnesses are all born from seeds, etc.": The seven consciousnesses are the effects; the seeds are the causes. Yet cause and effect are both called essence and characteristics. Essence is characteristic; there is no distinction. In general, although cause and effect are not definitively one, neither can they be definitively different, because they have no distinct nature. Regarding "taking these seeds to be the eighth consciousness": As the second fascicle of the Vijñaptimātratāsiddhi says, the ālayavijñāna has three characteristics. First is the causal characteristic, meaning that it holds seeds that are able to generate defiled and pure dharmas. Second is the effect characteristic, which is the entity of the active consciousness being the vipāka effect of wholesome and unwholesome karma. Third is the self-characteristic, which means that this seed and active [consciousness] embrace cause and effect as their self-characteristic. "Self-characteristic" means the sense of its own essence. Since it embraces cause and effect to be its own essence, seeds are therefore taken to be the eighth consciousness.