摩訶止觀 7.3

7.3

第五、識通塞者，亦名「知得失」，亦名「知字非字」。如上破法遍應通入無生；若不入者，當尋得失，必滯是非，不得一向作解。何者？若同外道，愛著觀空智慧，宜以四句遍破，能破如所破，令眾塞得通。若不執觀空智慧，則能破不如所破，但破塞、存通。如除膜養珠，破賊護將。若爾，即大導師善知通塞，將導眾人能過五百由旬。

Fifth, discerning passage and obstruction: this is also called 'knowing gain and loss,' and 'knowing what are letters and non-letters.' Through pervasively destroying phenomena as described above, one should unobstructed pass through and enter into non-arising; if one does not enter, one must examine gain and loss, for one is certainly stuck in right and wrong and cannot form a one-sided understanding. How so? If, like non-Buddhists, one craves and clings to the wisdom of contemplating emptiness, one should use the four phrases to pervasively destroy it, where that which destroys is like what is destroyed, so that all obstructions may gain passage. If one does not cling to the wisdom of contemplating emptiness, then that which destroys is not like what is destroyed: one only destroys obstructions and preserves passage. This is like removing a cataract while preserving the eye, or defeating bandits while protecting the general. If so, then like a great guide, one skillfully knows passage and obstruction, and can lead the multitude to cross the five hundred yojanas.