起信論疏筆削記 1.38

1.38

其猶下，二、喻也。此中四句，前二句喻真如不礙生滅，後二句喻生滅不礙真如。其者，指法之詞。猶，如也。波動，喻生滅染淨不同。水濕，喻真如一體無異。波以動為相，水以濕為性。初句反顯，以喻生滅門中無有異真如之染淨也，故云波無等。故即下，順喻，由不異故，遂能即於一心而辨生滅，故云即水等。即喻前文不變性而緣起染淨恒殊也。

From "It is just like..." onwards is the second part: the similes. Among these four lines, the first two lines illustrate that tathatā does not obstruct arising and ceasing, and the latter two lines illustrate that arising and ceasing do not obstruct tathatā. "It" (其) is a word pointing to the dharma. "Just like" (猶) means as if (如). The movement of the waves illustrates the differences between defilement and purity in arising and ceasing. The wetness of water illustrates that tathatā is of one essence without difference. The waves have motion as their mark; water has wetness as its nature. The first line reveals [the meaning] by negation, in order to illustrate that within the gate of arising and ceasing there is no defilement or purity distinct from tathatā; hence it says "waves have no [motion apart from water]," and so on. "Therefore, directly..." onwards is the direct simile: because they are not different, one is able to discern arising and ceasing right within the One Mind; hence it says "directly upon the water," and so forth. This illustrates the previous text's point that without changing its nature, the conditioned origination of defilement and purity is constantly distinct.