妙法蓮華經玄義 8.122

8.122

秖約此幻化即判四門。論云：「一切實一切不實，一切亦實亦不實，一切非實非不實。」佛於此四句，廣說第一義悉檀。一切實為有門者，若業若果善惡等法，乃至涅槃皆幻化。譬鏡中像，雖無實性，而有幻化頭等六分，為有門也。

It is precisely in terms of this illusion and conjuration that the four gates are distinguished. The treatise states: 'All is real; all is unreal; all is both real and unreal; all is neither real nor unreal.' In these four propositions, the Buddha extensively taught the paramārtha-siddhānta. Taking 'all is real' as the gate of existence: dharmas such as karma and fruit, wholesome and unwholesome, up to nirvāṇa, are all illusions and conjurations. Like an image in a mirror, although it lacks an actual nature, there are the illusory six parts such as the head; this is the gate of existence.