十二門論宗致義記 1.18

1.18

Question: If that is so, it should destroy the two truths, because cause and effect being identical with emptiness loses illusory existence and destroys the conventional truth, while emptiness being identical with cause and effect loses true emptiness and destroys the ultimate truth. Answer: It is precisely because they are not different that the two truths are preserved; if it were not so, then the two truths would be lost. How so? Cause and effect different from emptiness would not be illusory dharmas, and thus would lose the conventional truth; emptiness different from cause and effect would not be true emptiness, and thus would lose the ultimate truth. Therefore, that the two truths are preserved is due to non-difference; non-difference is the equality of the middle way; and thus it is by the middle way that there are two truths, which is precisely the two truths of the middle way.