摩訶止觀 5.230

5.230

若根塵合故有心生者，根塵各各有心故合生心？各各無心故合生心？若各各有合，則兩心生，墮自他性中；若各各無，合時亦無。譬如鏡、面，各有像故合生像？各無像故合生像？若各有像，應有兩像；若各無像，合不能生。若鏡、面合為一而生像者，今實不合，合則無像；若鏡、面離故生像者，各在一方，則應有像，今實不爾。根塵離合，亦得如是。如是推求，知心畢竟不從合生。又根塵各有心性，合則心生者，當檢此性為有？為無？如前破（云云）。

If mind arises from the union of sense faculty and sense object: does mind arise from their union because the sense faculty and sense object each individually possess mind, or because they each lack mind? If each individually possesses mind and they unite, then two minds would arise, which falls into the error of self-nature and other-nature. If each individually lacks mind, then when they unite there is also no mind. For example, regarding a mirror and a face: does an image arise from their union because each possesses an image, or because each lacks an image? If each possessed an image, there should be two images. If each lacked an image, their union could not produce one. If the mirror and face were to unite into one and thereby produce an image: in reality they do not unite now, and if they were united, there would be no image. If an image arose because the mirror and face are separated: when each is in a separate location, an image should arise, but in reality this is not so. The separation and union of sense faculty and sense object are also just like this. Searching in this way, one knows that mind ultimately does not arise from union. Furthermore, if the sense faculty and sense object each have the nature of mind and mind arises when they unite, one should examine whether this nature exists or does not exist, refuting it as before (and so on).