仁王護國般若波羅蜜多經疏 1.21

1.21

問：經明二諦，何不為宗？答：先德以彰，為宗無失。又此智證事理皆周，此以攝彼不別。

Question: The sūtra clarifies the two truths; why are they not taken as the central theme? Answer: Former masters have already clarified this; taking them as the central theme is without fault. Furthermore, this cognitive realization completely encompasses phenomena and principle; since this subsumes that, they are not separate.