起信論疏筆削記 6.21

6.21

疏　何故下，二、通前料揀。牃外難，可見。以所下，釋也。前云能示，顯詮旨不一；今云自體，顯詮旨不異。此門雖即能所有殊，非謂所詮在能詮外；今顯非外，故云自體等。斯則生滅是真如家相，真如是生滅家體，體相雖異，而不相離也。其猶波水雖異，豈得水在波外耶？故知其水是波之自體也。

In the commentary, from "Why..." onward, second, resolves the preceding inquiry. Citing the external challenge is evident. From "Because that which..." onward explains it. Previously it said "capable of displaying," showing that expresser and intent are not one; now it says "its self-essence," showing that expresser and intent are not different. Although in this gate there is a distinction between subject and object, it does not mean that what is expressed lies outside that which expresses; now to show that it is not outside, it therefore says "its self-essence, and so on." Thus arising and ceasing is the mark of tathatā, and tathatā is the essence of arising and ceasing; though essence and marks differ, they are not separate from each other. Just as waves and water differ, how could water be outside the waves? Therefore one knows that water is the waves' own essence.