俱舍論疏 30.156

30.156

論「必定應信至理不成故」，以有能依證所依我也。彼宗計我為實，念等德句。德依實句，不依餘故。故知我體亦有，不得言無。

On the Śāstra's statement: "One must certainly believe [...] because the principle is not established": This uses that which relies to prove the self that is relied upon. That school posits the self as a substance (dravya) and mindfulness and so forth as the category of qualities (guṇa-padārtha). Qualities rely on the category of substance and do not rely on anything else. Therefore one knows that the essence of the self also exists and cannot be said to be non-existent.