法華義疏 5.284

5.284

前取佛教通人出於三界悟入理故名為門，如後文云「以佛教門出三界苦」；今將所燒之言簡異前門，故知詺三界以之為門。如世人總舉一宅名之為門，或稱一家或言一戶。今亦然也，以八苦為能燒，三界為所燒，故云「所燒之門」也。

Earlier, taking the Buddha's teaching as leading people out of the three realms to awaken to and enter the principle, it was called a 'gate,' as the later text says, 'By means of the gate of the Buddha's teaching, escape the suffering of the three realms.' Now, by using the words 'burned,' it is distinguished from the previous gate; thus we know the three realms are designated as the gate. Just as worldly people collectively refer to a house as a 'door' (mén), or call it 'one family' or 'one household.' Here it is also like this: taking the eight sufferings as that which burns, and the three realms as that which is burned, it is therefore called 'the burned gate.'