觀心論疏 4.7

4.7

問：佛菩薩二乘四聖即是涅槃，六道十如即是生死，生死涅槃昇沈永別，云何得同在一心中耶？答：譬解者，氷喻六道，水喻四聖，而氷水一質，何妨生死涅槃體同？只為空有不相礙、二河不相妨，而在一心，故名不可思議境也。

Question: The four noble ones—buddhas, bodhisattvas, and the two vehicles—are nirvāṇa, while the ten suchnesses of the six destinies are birth-and-death; birth-and-death and nirvāṇa are as eternally distinct as ascending and sinking; how can they be together in a single mind? Answer: To explain by analogy: ice is a metaphor for the six destinies, and water is a metaphor for the four noble ones; yet ice and water are of one substance, so what prevents birth-and-death and nirvāṇa from having an identical substance? It is simply because emptiness and existence do not obstruct each other, and the two rivers do not hinder each other, while being present in a single mind; therefore it is called the inconceivable object.