請觀音經疏闡義鈔 1.25

1.25

「感應為宗」者，月蓋致請為感，三聖遠降為應，教興由此，故以為宗。然諸經或以因果為宗，但於今經明義不便。何者？因果語通、凡聖各有。如舍離人致請求救為因，未來證道為果，此凡有因果也。觀音昔在凡地為因，今居分證為果，此聖有因果也。今以凡雖有因果，但以感為名；聖雖有因果，但以應為名，故以感應為宗也。

As for 'taking stimulus and response as the gist': Candraprabha's making the invocation is the stimulus, and the three sages' descending from afar is the response; because the arising of the teaching originates from this, it is taken as the gist. However, various sūtras sometimes take cause and effect as their gist, but in this sūtra it is inconvenient for clarifying the meaning. Why? The phrasing of cause and effect is general, possessed by both ordinary beings and sages. For instance, the people of Vaiśālī making an invocation to seek salvation is the cause, and their future realization of the Way is the effect—this is ordinary beings possessing cause and effect. Avalokiteśvara formerly being on the stage of an ordinary being was the cause, and now residing in partial realization is the effect—this is the sage possessing cause and effect. Now, although ordinary beings possess cause and effect, they are designated only by 'stimulus'; although the sage possesses cause and effect, he is designated only by 'response'; therefore, stimulus and response are taken as the gist.