維摩經玄疏 6.58

6.58

三、明別教四門者，若用《中論》「亦名名」而辨四門者，即別教之四門，《大智論》四句亦得也。此別教四門意，正出《大涅槃經》，但多散說。約乳明四句譬，即是別教四門也。若明佛性，如乳有酪性，石有金性，力士額珠，即有門。若明石無金性，乳無酪性，眾生、佛性猶如虛空、大涅槃空、迦毘羅城空，即是空門也。《涅槃》又云「佛性亦有亦無者，云何為有？一切眾生悉皆有故；云何為無？從善方便而得見故」，又譬「如乳中亦有酪性，亦無酪性」，即是亦有亦無門。若明佛性即是中道，百非雙遣，故經譬云「乳中非有酪性，非無酪性」，即是非空非有門也。別教菩薩別稟此四門之教，因見佛性，住大涅槃，故此四句之說，即是別教之四門也。今一往約《涅槃經》文，分別別教四門之相。但此經文，或可圓教四門，至下圓教四門，自當料簡同異也。

Third, clarifying the four gates of the distinctive teaching: if one uses the Madhyamakaśāstra's "also called designation" to discern the four gates, they are the four gates of the distinctive teaching; the four propositions of the Dazhidulun are also acceptable. The intent of these four gates of the distinctive teaching directly comes from the Mahānirvāṇa Sūtra, but is mostly spoken dispersedly. The fourfold-proposition analogy explained with reference to milk is precisely the four gates of the distinctive teaching. If one clarifies that buddha-nature is like milk having the nature of curd, stone having the nature of gold, or the strongman's forehead jewel, that is the gate of existence. If one clarifies that stone has no nature of gold, milk has no nature of curd, and sentient beings and buddha-nature are like empty space, the emptiness of great nirvāṇa, and the emptiness of the city of Kapilavastu, that is the gate of emptiness. The Nirvāṇa [Sūtra] also says: "Regarding buddha-nature being both existent and non-existent: why is it existent? Because all sentient beings possess it. Why is it non-existent? Because it is seen through skillful expedients." And it also compares: "It is like milk both having the nature of curd and not having the nature of curd"—this is the gate of both existence and non-existence. If one clarifies that buddha-nature is precisely the middle way, with the hundred negations both discarded, hence the sūtra compares: "Milk neither has the nature of curd nor lacks the nature of curd"—this is the gate of neither emptiness nor existence. Bodhisattvas of the distinctive teaching distinctively receive the teaching of these four gates, and through it see buddha-nature and abide in great nirvāṇa; therefore the exposition of these four propositions is precisely the four gates of the distinctive teaching. Now I tentatively differentiate the characteristics of the four gates of the distinctive teaching with reference to the text of the Nirvāṇa Sūtra. However, this sūtra text might also be the four gates of the perfect teaching; when we come below to the four gates of the perfect teaching, their similarities and differences will naturally be evaluated.