維摩經玄疏 6.72

6.72

四、明用悉檀起非有非無門者，用四悉檀，亦類前有門用四悉檀，意可見也。

Fourth, explaining the use of the siddhāntas to generate the door of neither existence nor emptiness: using the four siddhāntas is also analogous to the above use of the four siddhāntas for the door of existence; the meaning can be seen.