俱舍論疏 29.135

29.135

論「若我與蘊一異俱不可說」者，牒彼計也。彼立三世、無為非不可說，第五法藏是不可說。若汝計我不可說與蘊一異者，五種爾焰亦應不可說。以我不可說異是第五故。亦不可說不異，非第五故。爾焰者，新譯名所知，舊譯名智母。真諦法師釋云：「我若異前四，則是可言，不應立第五為不可言。若不異前四，則唯有四，無第五不可言。故不可言第五及非第五。」

Regarding the Śāstra's statement: "If the self's identity with and difference from the aggregates are both ineffable": This takes up their claim. They establish that the three times and the unconditioned are not ineffable, but the fifth repository of phenomena is ineffable. If you claim that the self is ineffable as identical with or different from the aggregates, then the five kinds of jñeya should also be ineffable, because the self's ineffable difference is the fifth, and its ineffable non-difference is not the fifth. As for jñeya, the new translation calls it 'knowable' (suǒzhī), and the old translation calls it 'mother of cognition' (zhìmǔ). Dharma Master Paramārtha explained: "If the self were different from the preceding four, it would be expressible, and one should not establish the fifth as ineffable. If it were not different from the preceding four, there would only be four, and no fifth ineffable [repository]. Therefore it cannot be called either the fifth or not the fifth."