妙法蓮華經玄義 2.79

2.79

感應妙者，謂四句感應、三十六句感應、二十五感應、別圓感應。水不上升、月不下降，一月一時普現眾水；諸佛不來、眾生不往，慈善根力見如此事，故名感應妙。

The subtlety of stimulus and response: this refers to the four-phrase stimulus and response, the thirty-six-phrase stimulus and response, the twenty-five stimuli and responses, and the distinctive and perfect stimuli and responses. The water does not rise up, the moon does not descend, yet the one moon simultaneously appears universally in the many waters; the buddhas do not come, sentient beings do not go, yet through the power of compassionate good roots they see such things; hence it is named the subtlety of stimulus and response.