萬善同歸集 3.115

3.115

「第三、二諦並陳者，諸佛常依二諦說法，何以故？俗是真詮，了俗無性，即是真諦。故云：『若不得俗諦，不得第一義。』所以真不待立而常現；俗不待遣而自空。二諦雙存，如同波水。水窮波末，波水同時；波徹水源，動濕一際。

"Third: regarding 'Parallel presentation of the two truths,' the Buddhas always explain the Dharma relying on the two truths. Why? The conventional expresses the real; fully understanding that the conventional lacks self-nature is precisely the ultimate truth. Hence it is said: 'If one does not attain the conventional truth, one cannot attain the ultimate meaning.' Therefore, the real does not wait to be established to be constantly manifest; the conventional does not wait to be dismissed to be naturally empty. The two truths both persist, just like waves and water. Water penetrates to the tips of the waves—wave and water are simultaneous; waves reach down to the source of the water—movement and wetness are of a single boundary.