請觀音經疏闡義鈔 2.48

2.48

「菩薩」下，顯圓也。「是空亦空」者，以有叚中方便，故不滯於空，即是能空於空，故曰是空亦空。由有方便，故無染著。「而能」下，由無染著，故即空而假。「具修萬行通達佛道」者，達彼萬行即三諦理，乃由此智引趣菩提。

From "a bodhisattva" downward reveals the perfect [teaching]. "This emptiness is also empty": because one has the upāya of the provisional and the middle, one does not stagnate in emptiness; this is being able to empty emptiness, hence it is said "this emptiness is also empty." Because one has upāya, there is no defiled attachment. From "and capable of" downward: because there is no defiled attachment, emptiness is immediately the provisional. "Completely cultivating the myriad practices and thoroughly penetrating the Buddha Path" means penetrating those myriad practices as being the principle of the three truths; it is through this wisdom that one is guided to advance toward bodhi.