大般涅槃經義記 5.166

5.166

自下第二別釋如來虛空佛性，不同苦、集、滅、道四事，但即其實。苦中五句：一辯苦相，「所言苦者」牒前有苦，下辯其相，苦性非恒故曰「無常」，苦體虛妄，見實則捨，故云「可斷」；二「是實」下就苦顯實，苦家實性是一實諦，故名為實，不同向前所非之諦；三明如來不同前相，言「非苦」者不同向前所牒之苦，「非無常」者不同向前為無常相，「非可斷」者不同向前是可斷相；四「是故」下辯明如來唯即前實，以是如來不同向前苦等相故唯是其實；五以如來類空佛性。

From here on, the second [part] distinctly explains that the Tathāgata, space, and the buddha-nature are not identical to the four facts of suffering, origin, cessation, and path, but are identical solely to their reality. In suffering there are five phrases: First, it distinguishes the marks of suffering: 'what is called suffering' reiterates the existence of suffering above; below, it distinguishes its marks: because the nature of suffering is not eternal, it is called 'impermanent'; because the substance of suffering is false and discarded upon seeing the real, it is said to be 'severable.' Second, from 'is real' below, it reveals the real with respect to suffering: the real nature of suffering is the one real truth; therefore it is named real, unlike the truth negated previously. Third, it clarifies that the Tathāgata is unlike the former marks: stating 'is not suffering' means not being the same as the suffering reiterated previously; 'is not impermanent' means not being the same as the mark of impermanence; 'is not severable' means not being the same as the mark of severability. Fourth, from 'therefore' below, it analyzes and clarifies that the Tathāgata is identical solely to the prior real: because the Tathāgata is not the same as the former marks of suffering and so forth, it is solely its reality. Fifth, it compares space and the buddha-nature by analogy to the Tathāgata.