妙法蓮華經玄義 6.130

6.130

五、正就此經明妙十二部者，如脩多羅名直說，今經直說中道佛之智慧；不說六道、二乘、菩薩等法，唯說佛法，故直說為妙。

Fifth, directly clarifying the subtlety of the twelve genres in terms of this sūtra: as sūtra is named 'direct prose', the present sūtra directly expounds the Middle Way, the wisdom of the buddhas; it does not expound the dharmas of the six destinies, the two vehicles, bodhisattvas, and so forth, but expounds only the buddha-dharma; therefore the direct prose is subtle.