維摩經玄疏 6.65

6.65

First, explaining that the four doors of the Tripiṭaka teaching and the four doors of the shared teaching together enter the principle of partial truth: through their respective four doors, [practitioners of both teachings] equally perceive the primary truth and attain the two kinds of nirvāṇa; in this they are identical. Although the principle is one, the doors are distinct: since there is the difference between the skillful and crude crossings, there is the distinction between the two kinds of four doors that can provide access. Because the true principle is non-dual, the substance to which access is gained is one. For example, a prefectural city opens four gates, but the governor is only one; although those who enter from the four gates take distinct gates, the governor they see is merely one. The four doors of the Tripiṭaka teaching are like entering from the four side gates of the prefectural city; the four doors of the shared teaching are like entering from the four main gates. Although the side and main [gates] differ, entering to perceive the partial truth of paramārtha-satya and attaining the two kinds of nirvāṇa are identical.