大般涅槃經義記 7.336

7.336

下釋其相，先解不實，下解其實，先問後釋。釋中，初先開列七門，後廣辯釋。前開門中，「涅槃」是果，「佛性」是因，「如來、法、僧」即是菩提，「實相」世諦，「虛空」真諦，知此七法名實修行。有人一向說空為性，准此七門明空非性。

Below, it explains their characteristics: first it explains the unreal, and below it explains the real, first questioning and then explaining. Within the explanation, it first opens and enumerates seven gates, and afterwards extensively explains them. Within the earlier opening of the gates, "nirvāṇa" is the fruit, "buddha-nature" is the cause, "the Tathāgata, the Dharma, and the Saṅgha" are bodhi, "the true mark" is conventional truth, and "space" is ultimate truth; knowing these seven dharmas is called real cultivation. Some people persistently say that emptiness is the nature; in accordance with these seven gates, it is clarified that emptiness is not the nature.