成唯識論演祕 6.21

6.21

Answer: There are two explanations. One says: In terms of the twelve āyatanas, because the fundamental consciousness is subsumed under the manāyatana, it is called internal; attention is of the dharmāyatana, and therefore called external. Second: Only the eighth consciousness, because it is the fundamental cause for the arising of seeds and actual manifestations, is solely called internal; all other conditions, not being fundamental, are all called external. The Treatise relies on the latter explanation.