首楞嚴義疏注經 4.7

4.7

Pūrṇa was skilled in expounding the essentials of the Dharma, praised by the assembly as supreme; yet now hearing what the Buddha spoke, he has not fully grasped and understood it. It is like one whose ears are ruined facing a subtle sound far beyond a hundred paces: how could he clearly discern it? The primary truth is wondrous, subtle, and tranquil; this is the subtle sound. Hearing without understanding is equivalent to not hearing; this is like the deaf person. The path of speech is cut off, the place of mental activity is extinguished; this is exceeding a hundred paces. Expounding such Dharma to make me eliminate delusions, yet still trapped in a net of doubt without having fully undone the knots of hesitation; hence he draws this comparison.