淨名玄論 1.26

1.26

初門寄言明不二，後門假無言明不二，中間亦言亦無言明不二。問：經論之中多備四門，一無言門、二有言門、三亦言亦無言門、四非言非無言門。今何故但有三門而無第四門？答：餘經四句，各有所由。今此三門，義無不攝，如前說也。

The first gate relies on words to illuminate nonduality; the latter gate borrows wordlessness to illuminate nonduality; the middle relies on both words and wordlessness to illuminate nonduality. Question: Within the sūtras and treatises, the four gates are usually fully provided: first, the gate of wordlessness; second, the gate of having words; third, the gate of both words and wordlessness; fourth, the gate of neither words nor wordlessness. Why now are there only three gates and no fourth gate? Answer: The four propositions in other sūtras each have their specific reasons. Now, these three gates encompass all meanings without remainder, as explained previously.