八識規矩補註 2.25

2.25

Following wholesome and unwholesome karma, among the three realms, nine stages, and five destinies, this consciousness is the true vipāka fruit that is induced; because it is the master of the general recompense, it is the entity of the destinies and births. Why is it singularly this entity? Because it possesses four meanings: namely, being substantially existent, constant, pervasive, and unmixed, as the fruit induced by karma. Therefore, among the eight consciousnesses, only the eighth consciousness is entirely summoned by karma; the first six are partially summoned by karma; the seventh is not summoned by karma at all. The first six are also partially not summoned by karma, being of wholesome or unwholesome nature. An avyākṛta dharma is like dry earth that cannot hold itself together to form a single lump on its own, so it must directly depend on the power of wholesome and unwholesome karma—like using water and glue to blend with dry earth—to cause the avyākṛta dharma to form a vessel-like mass. Wholesome and unwholesome dharmas, like wood and stone, naturally form a vessel-like mass on their own without relying on external power, so they are not summoned by karma. When the verse says "arise according to the power of karma," it refers to this.