大般涅槃經義記 8.143

8.143

下次答上第二句問解性名義，即就明其常、樂、我、淨，眾生不見。「如汝所言以何義故名佛性者」牒舉前問。下釋有三：一總明佛性是其菩提，「中道有三」下別明佛性是其中道，三「十二緣智即是阿耨菩提種」下別明佛性是其種子。初中「即是中道種」者，性是中道，而與菩提作種子也。

Next, it answers the second question above, explaining the meaning of the name of the nature, and right therein explains its permanence, bliss, self, and purity, which sentient beings do not see. "As you have said, for what reason is it called the buddha-nature?" recapitulates and raises the earlier question. The explanation below has three parts: first, generally explaining that the buddha-nature is bodhi; from "the middle way has three" onward, specifically explaining that the buddha-nature is the middle way; third, from "the wisdom of the twelve links is the seed of anuttara-bodhi" onward, specifically explaining that the buddha-nature is its seed. In the first part, "it is the seed of the middle way" means that the nature is the middle way and serves as the seed for bodhi.